Optical disc recording apparatus, computer-readable recording medium recording a file management program, and optical disc

ABSTRACT

An optical disc recording apparatus for recording a video object onto an optical disc. A recording area of the optical disc is divided into a plurality of zones which each include a plurality of adjacent tracks. The optical disc recording apparatus includes: a reading unit for reading from the optical disc the sector information showing data assignment for sectors on the optical disc; a recording unit for recording the video object onto the optical disc; and a control unit for controlling the reading unit and the recording unit. The control unit detects at least one series of consecutive unassigned sectors on the optical disc by referring to the read sector information. Each series has a total size greater than a minimum size and is located within a single zone. The minimum size corresponds to a data amount that ensures uninterrupted reproduction of the video object. The control unit also controls the recording unit to record the video object into the detected series.

This a Rule 1.53(b) Divisional application of Ser. No. 09/692,831, filedOct. 20, 2000 which is a Rule 1.53(b) Divisional application of Ser. No.09/512,353, filed Feb. 24, 2000, now U.S. Pat. No. 6,285,872 B1 which isa Rule 1.53(b) Divisional application of Ser. No. 09/154,879, filed Sep.17, 1998 now U.S. Pat. No. 6,118,924.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to an optical disc recording apparatus, acomputer-readable recording medium recording a file management program,and an optical disc.

(2) Description of the Prior Art

Recently, recording mediums such as magneto optical discs (MO) have beenwidely used for recording data to be read by computers. Currently,practical uses of DVD (Digital Versatile Disc)-RAM discs are waited fordue to general expectation that DVD-RAMs will become a main recordingmedium of the next generation.

In conventional MOs, like HD (Hard Disc) or FD (Flexible Disc), theminimum unit in accessing data on discs is “sector” having severalkilobytes. Each file is recorded in one or more sectors.

Reading and writing of files from/onto discs are executed by computersas functions of a file system which is a part of operating systems (OS).A file system is defined, for example, in ISO/IEC13346.

According to a conventional technique, for example, when recording afile of 200 KB onto a recording medium with 2 KB-sectors, computers mustfind 100 unassigned sectors on the recording medium. The 100 unassignedsectors need not be physically consecutive. For example, when fourseparate groups respectively having 30, 30, 30, and 10 unassignedsectors are found on the recording medium, the file is divided into thefour groups of sectors. Each part of the file recorded in each group ofsectors, namely each group of consecutive sectors, is called “extent”.

In such a conventional technique, files can be divided and recorded intoa plurality of extents. This provides a merit that all the sectors on arecording medium can be used efficiently even after recording anddeleting of files on the medium are repeated a number of times.

However, conventional recording mediums and file systems have a problemthat uninterrupted reproduction of audio/video data (hereinafterreferred to as AV data) recorded on the recording mediums cannot beensured.

More specifically, when recording and deleting of files on a recordingmedium are repeated several times, the AV data may not be recorded inconsecutive sectors. The AV data may be divided and recorded into aplurality of extents, as described above. When this happens, thereproduction apparatus cannot achieve uninterrupted reproduction of theAV data due to a seek operation of an optical pickup that occurs as theoptical pickup moves between the plurality of extents.

For example, when a seek occurs between a sector at the innermostperiphery and a sector at the outermost periphery of a disc, the seektime amounts to several-hundred milliseconds. In case of moving images,such a seek of several-hundred milliseconds interrupts reproductionsince reproducing 30 frames per second is required for reproduction ofmoving images.

As described above, uninterrupted reproduction may not be ensured byconventional file systems. This is especially a serious problem for massstorages such as DVD-RAM on which, like VTR, a plurality of pieces of AVdata (e.g., TV programs) can be recorded, edited, and deleted.

Here, it should be reminded that recording mediums can also recordcomputer data, as well as AV data. Accordingly, particular attentionshould be paid on how to efficiently store both types of data on a disc.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an opticaldisc recording apparatus, a computer-readable recording medium recordinga file management program, and an optical disc which ensureuninterrupted reproduction of AV data and record various types of dataincluding AV data together and efficiently.

The above object is achieved by an optical disc recording apparatus forrecording a video object on an optical disc, where a recording area ofthe optical disc is divided into a plurality of zones which each includea plurality of adjacent tracks, and includes sector information showingdata assignment for sectors on the optical disc, the optical discrecording apparatus including: a reading unit for reading the sectorinformation from the optical disc; a recording unit for recording thevideo object onto the optical disc; and a control unit for controllingthe reading unit and the recording unit, where the control unit: detectsat least one series of consecutive unassigned sectors on the opticaldisc by referring to the read sector information, each series having atotal size greater than a minimum size and being located within a singlezone, the minimum size corresponding to a data amount that ensuresuninterrupted reproduction of the video object; and controls therecording unit to record the video object into the detected series.

With the above construction, the video object is recorded in a series ofconsecutive unassigned sectors with the total size greater than apredetermined size, the series without including a zone boundary. Thisis achieved by searching of such a series of consecutive unassignedsectors prior to the recording of the video object onto the opticaldisc. The predetermined size is set so that the uninterruptedreproduction is ensured in any types of reproduction apparatuses. As aresult, the video object recorded by the present optical disc recordingapparatus is reproduced by any types of reproduction apparatuses withoutgaps in the reproduced video and audio images (without missing frames).Also, the record area is divided into a plurality of zone areas torealize rotation control called Z-CLV (Zone-Constant Linear Velocity)during recording and reproduction. By doing so, a qualified recordingefficience is achieved without sacrificing the recording density of theoutermost periphery of the optical disc. Also, the uninterruptedreproduction is ensured since the video object does not outstep the zoneboundary.

In the above optical disc recording apparatus, the recording area of theoptical disc may be divided into a plurality of 2 KB sectors, with eachset of 16 consecutive sectors forming one ECC block, the video object iscomposed of a plurality of packs, each pack having a size of 2 KB, theminimum size is the number of ECC blocks which is represented as “N_ecc”in the following formula: N_ecc=Vo*Tj/((16*8*2048)*(1−Vo/Vr)), where“Tj” represents a maximum jump time of an optical pickup of areproduction apparatus, “Vr” represents an input transfer rate (Mbps) ofa track buffer of the reproduction apparatus, and “Vo” represents aneffective output transfer rate (Mbps) of the track buffer.

With the above construction, the predetermined size for ensuring theuninterrupted reproduction can be obtained in case defective sectors arenot included in the series of consecutive unassigned sectors.

In the above optical disc recording apparatus, the recording area of theoptical disc is divided into a plurality of 2 KB sectors, with each setof 16 consecutive sectors forming one ECC block, the video object iscomposed of a plurality of packs, each pack having a size of 2 KB, theminimum size is the number of ECC blocks which is represented as “N_ecc”in the following formula: N_ecc=dN_ecc+Vo*Tj/((16*8*2048)*(1−Vo/Vr)),where dN_ecc is a number of ECC blocks, in a series of consecutiveunassigned sectors, that include defective sectors, “Tj” represents amaximum jump time of an optical pickup of an reproduction apparatus,“Vr” represents an input transfer rate (Mbps) of a track buffer of thereproduction apparatus, and “Vo” represents an effective output transferrate (Mbps) of the track buffer.

With the above construction, the predetermined size for ensuring theuninterrupted reproduction can be obtained in case defective sectors areincluded in the series of consecutive unassigned sectors.

In the above optical disc recording apparatus, the effective transferrate Vo may be found according to the following formula:

Vo=(N_pack*2048*8)*(27 M/(SCR_first_next−SCR_first_current)

where N_pack is the total number of packs included in the video objectthat should be recorded in N_ecc ECC blocks, SCR_first_current is a time(in 1/(27 mega) seconds) at which the track buffer of the reproductionapparatus should output the first pack of the video object, andSCR_first_next is a time (in 1/(27 mega) seconds) at which the trackbuffer of the reproduction apparatus should output the first pack of thefollowing video object.

With the above construction, it is possible to obtain, based on theeffective output transfer rate, the predetermined size for video objectswith a variable bit rate. This achieves, for example, an efficient useof optical disc having a small amount of unassigned areas.

In the above optical disc recording apparatus, the control unit maygenerate management information showing areas of the optical disc wherethe video object has been recorded by the recording unit and controlsthe recording unit to record the generated management information ontothe optical disc, and when the reading unit reads out managementinformation from the optical disc, the control unit refers to the readmanagement information as well as the sector information to detect theseries.

With the above construction in which the management information isrecorded on the optical disc, it is possible to detect unassigned areasat high speed and without difficulty.

The above object is also achieved by a computer-readable recordingmedium prestoring a file management program for recording a video objectonto an optical disc, the file management program being to be run by acomputer which includes: a reading unit for reading data from an opticaldisc; and a recording unit for recording data onto the optical disc,where a recording area of the optical disc is divided into a pluralityof zones which each include a plurality of adjacent tracks, and includessector information showing data assignment for sectors on the opticaldisc, the file management program including the following steps to beexecuted by the computer: a reading step for reading the sectorinformation from the optical disc; a detecting step for detecting atleast one series of consecutive unassigned sectors on the optical discby referring to the read sector information, each series having a totalsize greater than a minimum size and being located within a single zone,the minimum size corresponding to a data amount that ensuresuninterrupted reproduction of the video object; and a recording step forrecording the video object into the detected series.

With the above construction in which the computer runs the filemanagement program, it is possible to record the video object into theseries of consecutive unassigned sectors which is larger than apredetermined size. This ensures the uninterrupted reproduction of thevideo object.

The above object is also achieved by a computer-readable optical discincluding a data recording area, where the data recording area isdivided into a plurality of zones which each include a plurality ofadjacent tracks, and the data recording area includes: sectorinformation showing data assignment for sectors on the optical disc; andmanagement information showing areas of the optical disc where a videoobject has been recorded and are located within a single zone.

The above object is also achieved by a computer-readable optical discincluding a data recording area, where the data recording area isdivided into a plurality of blocks which each include a plurality ofconsecutive sectors, and the data recording area includes: an area forrecording sector information showing data assignment for sectors on theoptical disc; and a management area for recording block informationshowing data assignment for blocks on the optical disc.

With the above construction, it is possible to record data in units ofsectors or blocks. Each block includes a plurality of consecutivesectors. Accordingly, even if one file is divided and recorded into aplurality of extents, the size of the extent is larger than the size ofthe block at the minimum. As a result, it is possible to ensure theuninterrupted reproduction of the video data recorded on the presentoptical disc by preventing interruptions which are cased by occurrencesof seek operations in the reproduction apparatus. Furthermore, datamanagement in units of sectors and blocks are performed togetherdepending on the types of data. This achieves efficient use of therecording area of the optical disc.

In the above computer-readable optical disc, when the block informationshows that blocks have been assigned to data that is mainly composed ofvideo data, the sector information may show that all sectors in theassigned blocks have been assigned.

With the above construction, even if data is recorded by a conventionalfile system which uses a file management system managing data in unitsof sectors, the blocks assigned to video data are not overwritten byanother data. Such a computer-readable optical disc is suitable foruninterrupted reproduction.

In the above computer-readable optical disc, a block size represented as“L” may satisfy the following formula:

L>T*Vin*Vout/′(Vin−Vout),

where “L” (bits) represents the block size, “T” (seconds) represents aseek time of a reproduction apparatus, “Vin” represents an inputtransfer rate (Mbps) of a buffer of the reproduction apparatus, and“Vout” represents an effective output transfer rate (Mbps) of thebuffer.

In the above computer-readable optical disc, when the block informationshows that blocks have been assigned to data that is not video data, thesector information may show that among sectors in the assigned blocks,only sectors recording the data have been assigned.

With the above construction, it is possible to record data other thanvideo data (non-video) into unassigned sectors in blocks which have beenassigned to non-video data. With this arrangement, even if video dataand other types of data are recorded in mixture, the uninterruptedreproduction is ensured, and both of video and other types of data arestored efficiently.

In the above computer-readable optical disc, the data recording area maybe divided into a plurality of zones which each include a plurality ofadjacent tracks, and each of the plurality of blocks is included in anyone of the plurality of zones.

With the above construction, the record area is divided into a pluralityof zone areas to realize Z-CLV. By doing so, a qualified recordingefficiency is achieved without sacrificing the recording density of theoutermost periphery of the optical disc. Also, the uninterruptedreproduction is ensured since the video object does not outstep the zoneboundary.

In the above computer-readable optical disc, blocks in each zone mayhave the same size except a block that is adjacent to a zone boundary,and the block that is adjacent to the zone boundary has a size beingequal to or larger than the size of the other blocks.

With the above construction, it is possible to use the data recordingarea efficiently since one block in each zone has a size larger than thecommon size of the other blocks.

In the above computer-readable optical disc, the block that is adjacentto the zone boundary may include a sector having a maximum sectoraddress in the current zone, and the management area includes a maximumblock length table which shows, for each zone, sizes of blocks whicheach include the sector having the maximum sector address in a zone.

With the above construction, it is possible to manage variable-lengthblocks around the zone boundary without difficulty.

In the above computer-readable optical disc, an error correction codemay be attached to every predetermined number of consecutive sectors,and each block may be composed of an integral multiple of thepredetermined number of consecutive sectors.

With the above construction, it is possible for therecording/reproducing apparatus to record and reproduce continuouslywithout generating overhead since each block is composed of an integralmultiple of the predetermined number of consecutive sectors.

The above object is also achieved by an optical disc recording apparatusfor recording data onto an optical disc which includes: a data recordingarea divided into a plurality of sectors; and a management area forrecording sector information showing data assignment for sectors on theoptical disc and block information showing data assignment for blocks onthe optical disc, the optical disc recording apparatus including: areading unit for reading the block information and the sectorinformation from the optical disc; a judging unit for judging a type ofthe data to record or delete the data, the type being classified into afirst type and a second type; a first specifying unit for, when thejudging unit judges that the data is the first type, specifying, basedon the read block information, either of: unassigned blocks in which thedata is to be recorded: and blocks in which the data has already beenrecorded; a second specifying unit for, when the judging unit judgesthat the data is the second type, specifying, based on the read sectorinformation, either of: unassigned sectors in which the data is to berecorded; and sectors in which the data has been recorded; a dataupdating unit for either of recording and deleting first-type datainto/from the blocks specified by the first specifying unit and foreither of recording and deleting second-type data into/from the sectorsspecified by the second specifying unit; and an assignment updating unitfor updating at least one of the sector information and the blockinformation in accordance with operations of the data updating unit.

With the above construction, it is possible to record data in units ofsectors or blocks. Each block includes a plurality of consecutivesectors. Accordingly, even if one file is divided and recorded into aplurality of extents, the size of the extent is larger than the size ofthe block at the minimum. As a result, it is possible to ensure theuninterrupted reproduction of the video data recorded on the presentoptical disc by preventing interruptions which are cased by occurrencesof seek operations in the reproduction apparatus. Furthermore, datamanagement in units of sectors and blocks are performed togetherdepending on the types of data. This achieves efficient use of therecording area of the optical disc.

In the above optical disc recording apparatus, the assignment updatingunit may include: a block information updating unit for, when the firstspecifying unit specifies unassigned blocks, updating the blockinformation by changing indication of the specified blocks from“unassigned” to “assigned”; and a sector information updating unit for,when the block information updating unit updates the block informationby changing indication of the specified blocks from “unassigned” to“assigned,” updating the sector information by changing indication ofall sectors included in the specified blocks from “unassigned” to“assigned.”

With the above construction, even if data is recorded by a conventionalfile system which uses a file management system managing data in unitsof sectors, the blocks assigned to video data are not overwritten byanother data. Such a computer-readable optical disc is suitable foruninterrupted reproduction.

In the above optical disc recording apparatus, the block informationupdating unit, when the first specifying unit specifies blocks which areassigned to a piece of first-type data to be deleted, updates the blockinformation by changing indication of the specified blocks from“assigned” to “unassigned,” and the sector information updating unit,when the block information updating unit updates the block informationby changing indication of the specified blocks from “assigned” to“unassigned,” updates the sector information by changing indication ofall sectors included in the specified blocks from “assigned” to“unassigned.”

With the above construction, it is possible to use the data recordingarea efficiently by recording the first-type data and the second-typedata in mixture since all the sectors in a block are released when thefirst-type data is deleted.

In the above optical disc recording apparatus, the block information mayshow whether each block is: (1) unassigned data; (2) assigned first-typedata which is mainly composed of video data; or (3) assigned second-typedata which is mainly composed of data other than the first-type data,where the assignment updating unit includes: a first updating unit forupdating the block information; and a second updating unit for updatingthe sector information, where the first updating unit, when the secondupdating unit updates the sector information by changing indication ofany sectors included in unassigned blocks to “assigned,” updates theblock information by changing indication of the unassigned blocks from“unassigned” to “second-type data assigned,” and the second updatingunit, when the first updating unit updates the block information bychanging indication of blocks from “unassigned” to “first-type dataassigned,” updates the sector information by changing indication of allsectors included in the blocks to “assigned.”

With the above construction, it is possible to-manage the data recordingarea without difficulty by recording the first-type data and thesecond-type data in mixture.

The above object is also achieved by a computer-readable recordingmedium prestoring a file management program for recording data onto anoptical disc which includes: a data recording area divided into aplurality of sectors; and a management area for recording sectorinformation showing data assignment for sectors on the optical disc andblock information showing data assignment for blocks on the opticaldisc, the file management program including the following steps to beexecuted by the computer: a reading step for reading the blockinformation and the sector information from the optical disc; a judgingstep for judging a type of the data to record or delete the data, thetype being classified into a first type and a second type; a firstspecifying step for, when in the judging step it is judged that the datais the first type, specifying, based on the read block information,either of: unassigned blocks in which the data is to be recorded: andblocks in which the data has already been recorded; a second specifyingstep for, when in the judging step it is judged that the data is thesecond type, specifying, based on the read sector information, eitherof: unassigned sectors in which the data is to be recorded; and sectorsin which the data has been recorded; a data updating step for either ofrecording and deleting first-type data into/from the blocks specified bythe first specifying unit and for either of recording and deletingsecond-type data into/from the sectors specified in the secondspecifying step; and an assignment updating step for updating at leastone of the sector information and the block information in accordancewith operations in the data updating step.

With the above construction, it is possible to record data in units ofsectors or blocks. Each block includes a plurality of consecutivesectors. Accordingly, even if one file is divided and recorded into aplurality of extents, the size of the extent is larger than the size ofthe block at the minimum. As a result, it is possible to ensure theuninterrupted reproduction of the video data recorded on the presentoptical disc by preventing interruptions which are cased by occurrencesof seek operations in the reproduction apparatus. Furthermore, datamanagement in units of sectors and blocks are performed togetherdepending on the types of data. This achieves efficient use of therecording area of the optical disc.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings which illustrate a specificembodiment of the invention. In the drawings:

FIG. 1 shows the appearance and the recording area of the DVD-RAM discwhich is the optical disc of the present invention described inEmbodiment 1;

FIG. 2 shows the cross-section and surface of a DVD-RAM cut at theheader of a sector;

FIG. 3A shows the plurality of zone areas 0-23 and other areas providedon a DVD-RAM;

FIG. 3B shows a horizontal arrangement of the zone areas 0-23 and otherareas;

FIG. 3C shows logical sector numbers (LSNs) in the volume area;

FIG. 3D shows logical block numbers (LBNS) in the volume area;

FIG. 4 shows a hierarchical relation between zone areas, ECC blocks, andsectors;

FIG. 5 shows a last-block-length table;

FIG. 6 shows a sector management table and an AV block management table

FIG. 7 shows the AV block management table and the sector managementtable (space bit map) which are both included in the file systemmanagement information recorded in the volume area;

FIG. 8 shows information included in the file system managementinformation other than the sector management table and the AV blockmanagement table shown in FIG. 6;

FIG. 9 shows a hierarchical directory structure corresponding to themanagement information shown in FIG. 8;

FIG. 10 shows the linkage between the file entries and directoriesrewritten in accordance with the directory structure;

FIG. 11A shows a detailed data structure of file entry;

FIG. 11B shows the data structure of the allocation descriptor;

FIG. 11C shows an interpretation of upper two bits of extent length ofallocation descriptor;

FIG. 12A shows a detailed data structure of the file identificationdescriptors for directory;

FIG. 12B shows a detailed data structure of the file identificationdescriptors for file;

FIG. 13 shows a model of buffering of AV data into the track buffer, theAV data being read from the DVD-RAM disc by a reproduction apparatus

FIG. 14 shows the construction of a system including the optical discrecording/reproduction apparatus of the embodiment;

FIG. 15 is a block diagram showing the hardware structure of the DVDrecorder 10;

FIG. 16 is a block diagram showing the construction of the MPEG encoder2;

FIG. 17 is a block diagram showing the construction of the MPEG decoder4;

FIG. 18 is a function block diagram showing the construction of the DVDrecorder 10 based on the functions of the components;

FIG. 19 shows the changes in the AV block management table and the spacebit map when AV data is recorded;

FIG. 20 shows the changes in the AV block management table and the spacebit map when AV data is deleted;

FIG. 21 shows a list of commands supported by the file system unit 102for the file management;

FIG. 22 shows an arrangement of buttons of the remote controller 6;

FIG. 23 shows guidance images;

FIG. 24 shows the bit rate and resolution for each of the quality types“high,” “standard,” and “time-ensuring;”

FIG. 25A is a flowchart showing the manual recording process performedby the AV file system unit 103 of the DVD recorder unit 10;

FIG. 25B is a flowchart showing the programmed recording processperformed by the AV file system unit 103 of the DVD recorder unit 10;

FIG. 26 is a flowchart showing the process performed by the AV filesystem unit 103 having received the AV-WRITE command;

FIG. 27 is a flowchart showing the process of deleting AV filesperformed by the common file system unit 104;

FIG. 28A shows AV files before and after deletion;

FIG. 28B shows the changes in the AV block management table and thespace bit map corresponding to the deletion;

FIG. 29 is a flowchart showing the process of recording non-AV filesperformed by the common file system unit 104;

FIG. 30 is a flowchart showing the process of deleting non-AV filesperformed by the common file system unit 104;

FIG. 31A shows non-AV files before and after deletion;

FIG. 31B shows the changes in the AV block management table and thespace bit map corresponding to the deletion;

FIG. 32 shows the second construction example of the AV block managementtable;

FIG. 33 shows the third construction example of the AV block managementtable;

FIG. 34 shows the fourth construction example of the AV block managementtable;

FIG. 35 shows the fifth construction example of the AV block managementtable;

FIG. 36A shows a specific example of the management information;

FIG. 36B shows a space bit map corresponding to the managementinformation shown in FIG. 36A;

FIG. 37 is a function block diagram showing the construction of the DVDrecorder 10 of Embodiment 2 based on the functions of the components;

FIG. 38 is a flowchart showing the recording process performed by the AVrecorder unit;

FIG. 39 shows a model of buffering of AV data into the track buffer inthe reproduction apparatus;

FIG. 40 is a flowchart showing the recording process in the DVD recorderof Embodiment 3;

FIG. 41 shows a free space list; and

FIG. 42 is a flowchart detailing the procedure of assigning the pseudoconsecutive record.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following are the table of contents of the present section.

(1) Embodiment 1

(1-1) Optical Disc

(1-1-1) Physical Structure of Optical Disc

(1-1-2) File System Management Information (Part 1)

(1-1-3) File System Management Information (Part 2)

(1-1-4) Minimum Size of AV Block

(1-2-1) Entire System

(1-2-2) Hardware Structure of DVD Recorder 10

(1-2-3) Function Block Diagram

(1-2-4) Commands Executed by File system Unit 102

(1-3) Recording/Deleting

(1-3-1) Manual Recording of AV Data

(1-3-2) Programmed Recording of AV Data

(1-3-3) Deleting of AV Data

(1-3-4) Recording of Non-AV Data

(1-3-5) Deleting of Non-AV Data

(2) Embodiment 2

(2-1) Optical Disc

(2-1-1) Pseudo Consecutive Record

(2-1-2) Assignment of Pseudo Consecutive Records

(2-1-3) Pseudo Consecutive Record Assignment Management Information andSpace Bit Map

(2-2) Recording/Reproducing Apparatus

(2-2-1) System and Hardware Structure

(2-2-2) Function Block Diagram

(2-3-1) Recording of AV Files

(3) Embodiment 3

(3-1) Minimum Size of Pseudo Consecutive Record

(3-2) Recording of AV files

Now, an optical disc and an optical disc recording apparatus of thepresent invention are described in several embodiments with theabove-listed headings.

(1) Embodiment 1

(1-1) Optical Disc

(1-1-1) Physical Structure of Optical Disc

FIG. 1 shows the appearance and the recording area of a DVD-RAM discwhich is an optical disc. As shown in the figure, the DVD-RAM disc has alead-in area at its innermost periphery and a lead-out area at itsoutermost periphery, with the data area in between. The lead-in arearecords the necessary reference signals for the stabilization of a servoduring access by an optical pickup, and identification signals toprevent confusion with other media. The lead-out area records the sametype of reference signals as the lead-in area.

The data area, meanwhile, is divided into sectors which are the smallestunit by which the DVD-RAM can be accessed. Here, the size of each sectoris set at 2 KB. The data area is also divided into a plurality of AVblocks which each are a group of consecutive sectors. The size of eachAV block is set so that the uninterrupted reproduction the reproductionapparatus is ensured even if a seek operation occurs. In the presentembodiment, the size is set to about 7 MB. The data area, divided intosectors and AV blocks as described above, is managed as follows. “Non-AVdata,” data other than AV data, is assigned areas in units of sectors,while AV data is assigned areas in units of AV blocks. Non-AV data ismanaged in units of sectors; AV data is managed in units of AV blocks.Non-AV data is also recorded in sectors in AV blocks. Each AV block ismanaged not to include AV data and non-AV data in mixture.

FIG. 2 shows the cross-section and surface of a DVD-RAM cut at theheader of a sector. As shown in the figure, each sector is composed of apit sequence that is formed in the surface of a reflective film, such asa metal film, and an uneven part.

The pit sequence is composed of 0.4 μm˜1.87 μm pits that are carved intothe surface of the DVD-RAM to show the sector address.

The uneven part is composed of a concave part called a “groove” and aconvex part called a “land”. Each groove and land has a recording markcomposed of a matal film capable of phase change attached to itssurface. Here, the expression “capable of phase change” unit that therecording mark can be in a crystalline state or a non-crystalline statedepending on whether the metal film has been exposed to a light beam.Using this phase change characteristic, data can be recorded into thisuneven part. While it is only possible to record data onto the land partof an MO disc, data can be recorded onto both the land and the grooveparts of a DVD-RAM, meaning that the recording density of a DVD-RAMexceeds that of an MO disc. Error correction information is provided ona DVD-RAM for each group of 16 sectors. In the present embodiment, eachgroup of 16 sectors that is given an ECC (Error Correcting Code) iscalled an ECC block.

On a DVD-RAM, the data area is divided into a plurality of zone areas torealize rotation control called Z-CLV (Zone-Constant Linear Velocity)during recording and reproduction.

FIG. 3A shows the plurality of zone areas provided on a DVD-RAM. Asshown in the figure, a DVD-RAM is divided into 24 zone areas numberedzone 0 to zone 23. Each zone area is a group of tracks that are accessedusing the same angular velocity. In this embodiment, each zone areacontains 1888 tracks. The rotational angular velocity of the DVD-RAM isset separately for each zone area, with this velocity being higher thecloser a zone area is located to the inner periphery of the disc. Thisensures that the optical pickup can move at a constant velocity whileperforming access within a single zone area. By doing so, the recordingdensity of DVD-RAM is raised, and rotation control is made easier duringrecording and reproduction.

FIG. 3B shows a horizontal arrangement of the lead-in area, the lead-outarea, and the zone area 0-23 that were shown in FIG. 3A.

The lead-in area and lead-out area each have a DMA (Defect ManagementArea) inside. The DMA records: position information showing thepositions of sectors found to include defects; and replacement positioninformation showing the positions of the sectors replacing the defectivesectors located in a replacement area.

Each zone area has a user area on the inside, and the replacement areaand an unused area are provided at the boundary between zone areas. Theuser area is an area that can be used by the file system as a recordingarea. The replacement area is used to replace defective sectors whensuch defective sectors are found. The unused area is an area that is notused for recording data. Only two tracks are assigned as the unusedarea, with such unused area being provided to prevent mistakenidentification of sector addresses. This is because while sectoraddresses are recorded at a same position in adjacent tracks within thesame zone, for Z-CLV the sector addresses are recorded at differentpositions in adjacent tracks at the zone boundary.

In this way, sectors which are not used for data recording exist at theboundaries between zone areas. Therefore, on a DVD-RAM logical sectornumbers (LSN: Logical Sector Number) are assigned to physical sectors ofthe user area in order starting from the inner periphery toconsecutively show only the sectors used for recording data.

As shown in FIG. 3C, the area that records user data and is composed ofsectors that have been assigned LSNs is called volume area.

Also, as shown in FIG. 3D, in the innermost and outermost peripheries,volume structure information is recorded to be used to deal with thedisc as a logical volume. The rest of the volume area except the areasfor recording the volume structure information is called partition area.The partition area records files. The logical block numbers (LBN:Logical Block Number) are assigned to sectors of the partition area inorder starting from the first sector.

FIG. 4 shows a hierarchical relation between zone areas, ECC blocks, andsectors. As shown in the drawing, each zone area includes 224 ECC blocks(3584 sectors). However, the number of sectors in a zone is notnecessary be an integral multiple of 224, or the number of ECC blocks.Therefore, the size of the last AV block in a zone is set to larger than224 ECC blocks so that the number of sectors in a zone becomes anintegral multiple of 224. For this purpose, DVD-RAM discs record a tablewhich shows the size of the last block in each zone, as a part ofmanagement information.

FIG. 5 shows a last-block-length table. The last-block-length tableshows, for each zone, the length of the last AV block related to “lastLBN.” The length of the last AV block is represented by the number ofECC blocks included in the AV block. The “last LBN” column shows the LBNof the last sector (zone end), namely, the last sector adjacent to thezone boundary, to indicate the position of the zone boundary.

As described above, the length of the last AV block is set to avariable-length. This prevents each AV block from including a zoneboundary. With this arrangement, it is possible to use the recordingarea on the disc efficiently.

(1-1-2) File System Management Information (Part 1)

Here, the file system structure of DVD-RAM is described. The file systemof the present embodiment complies with ISO/IEC13346. In addition, thefile system manages the AV data in units of AV blocks.

FIG. 6 shows a sector management table and an AV block management table.The sector management table is recorded in the partition area of thevolume area and is included in the file system management information.The drawing also shows a hierarchical relation between the volume area,sectors, and contents of the sectors.

The first layer shows the volume area shown in FIG. 3D.

The second layer shows sector areas which includes the sector managementtable and the AV block management table. The sector areas are includedin the partition area. The sector management table (also called a spacebit map) showing the data assignment status for each sector is recordedin the sector areas with LBNs 0-79. The AV block management tableshowing the data assignment status for each AV block is recorded in thesector areas with LBNs 84 and 85.

As shown in the third layer, the “space bit map” column shows whethereach sector included in the partition area is assigned or not-assigned.In this example, the assignment state of each sector is indicated by onebit. For example, each sector for logical block numbers 0-79 is givenbit “0” (indicating “assigned”) since these sectors have already beenassigned as a space bit map. Similarly, each sector for logical blocknumbers 0-84 is given bit “0” (assigned) since these sectors havealready been assigned as the AV block management block. As understoodfrom these examples, each bit in the space bit map is written as “0”when a file or a part of a file is to be recorded or has been recordedby the user or the application in the current sector, otherwise writtenas “1.”

The AV block shown in the third layer shows for each AV block in thepartition area, with two bits for each AV block, whether the current AVblock is unassigned (00), assigned to AV data (01), assigned to non-AVdata (10), or reserved (11). For example, the AV block 0 is given bits“10” (indicating “assigned to non-AV data”) since the AV block 0 hasalready been assigned as the space bit map and the AV block managementtable which are both non-AV data. When certain AV blocks are shown asassigned to AV data in the AV block management table, all the sectorsincluded in the AV blocks are shown as assigned in the space bit map.This makes it possible to prevent mixture of AV and non-AV data in eachAV block, and secures AV data consecutive recording areas.

FIG. 7 shows relationships between the AV block management table and thespace bit map.

On the left-hand side of the figure, the AV block management table isshown. The table includes an arrangement of a plurality of pieces oftwo-bit data which each shows the assignment status of AV block. In thisexample, the AV blocks (AV_BLK in the drawing) #0-#2 are written as “10”(non-AV data); the AV blocks #3-#75 are written as “01” (AV data); andthe AV blocks #76 and after are written as “00” (unassigned).

On the right-hand side of the figure, the space bit map is shown. Inthis example, the assignment status of the sectors included in the AVblocks #0, #3, and #79 is shown in the blocks encircled by dotted lines.The AV block #0 has been assigned to non-AV data. As a result, in acorresponding part in the space bit map, it is shown that sectors havingbeen recorded non-AV data are written as “0” (assigned); sectors havingnot been recorded non-AV data are written as “1” (unassigned). The AVblock #3 has been assigned to AV data. As a result, in a correspondingpart in the space bit map, it is shown that all the sectors are writtenas “0” (assigned). The AV block #79 has not been assigned yet. As aresult, in a corresponding part in the space bit map, it is shown thatall the sectors are written as “1” (unassigned).

It should be noted here that the AV block management table may berecorded as data for the file system, as the space bit map is, or may berecorded as one file. In the latter case, the AV block management tableis managed as a non-AV data file.

In the present embodiment, the AV block management table has a tablestructure. However, it may have a list structure.

(1-1-3) File System Management Information (Part 2)

FIG. 8 shows information included in the file system managementinformation other than the sector management table and the AV blockmanagement table shown in FIG. 6. The drawing shows hierarchically thevolume area, sectors, and the contents of the sectors. The arrows{circle around (1)}-{circle around (7)} show the order in which thestorage position of the file “Movie1.VOB” is detected in accordance withthe management information shown in the drawing.

The first layer of the drawing shows the volume area shown in FIG. 3D.

The second layer shows various kinds of management information such as afile set descriptor, end descriptor, file entry, and directory. Thesekinds of information comply with the file system defined inISO/IEC13346. The file system defined in ISO/IEC13346 achieves ahierarchical directory management. FIG. 9 shows a hierarchical directorystructure corresponding to the management information shown in FIG. 8.In FIG. 9, ovals represent directories, and rectangles represent files.The root directory branches to a directory “VIDEO” and two files“File1.DAT” and “File2.DAT.” The directory “VIDEO” branches to threefiles “Movie1.VOB,” “Movie2.VOB,” and “Movie3.VOB.” The managementinformation of FIG. 8 corresponds to the directory structure. Note thateach file recording area shows only “Movie1.VOB.” in this example.

The file set descriptor with LBN 80 in the second layer shows an LBN ofa sector in which a file entry of the root directory is recorded. Theend descriptor with LBN 81 shows the end of a file set descriptor.

Each file entry (e.g., LBN 82, 584, or 3585) is recorded for each file(including directory) and shows a storage position of a file or adirectory. File entries for files and directories have the same formatso that a hierarchical directory structure can be constructed as onedesires.

Each directory (e.g., LBN 83, or 585) shows a storage position of a fileentry for each file and each directory included in a directory.

The third layer of this example includes three file entries and twodirectories. The file entries and directories are traced by the filesystem, and have a data structure constructed so that a storage positionof a predetermine file can be traced no matter how the directorystructure is constructed.

Each file entry includes an allocation descriptor showing a storageposition of a file or a directory. When the file or the directory isdivided into a plurality of extents, the file entry includes a pluralityof allocation descriptors for each extent. For example, file entrieswith LBN 82 and 584 each include one allocation descriptor. This meansthat none of these files is divided into a plurality of extents. Incontrast, the file entry with LBN 3585 includes two allocationdescriptors, indicating that the file is composed of two extents.

Each directory includes a file identification descriptor showing, foreach file and directory included in the current directory, a storageposition of the current file entry. As indicated by the file entries anddirectories shown in this figure, the storage position of the file“root/video/Movie1.VOB” is traced in the order of: file setdescriptor→{circle around (1+L )}→file entry (root)→{circle around (2+L)}→directory (root)→{circle around (3+L )}→file entry (video)→{circlearound (4+L )}→directory (video)→{circle around (5+L )}→file entry(Movie1)→{circle around (6)}{circle around (7)}→file (extents #1 and #2of Movie1.VOB).

FIG. 10 shows the linkage between the file entries and directoriesrewritten in accordance with the directory structure. In the drawing,the root directory includes file identification descriptors respectivelyfor: a parent dierectory (the parent of the root is the root itself), aVIDEO directory, file “File1.DAT,” and file “File2.DAT.” Also, the VIDEOdirectory includes file identification descriptors respectively for: aparent dierectory (root), file “Movie1.VOB,” file “Movie2.VOB,” and file“Movie3.VOB.” The storage position of file “Movie1.VOB” is detected bytracing in the order of {circle around (1+L )} to {circle around(6)}{circle around (7)}.

FIG. 11A shows a detailed data structure of file entry. As shown in thedrawing, the file entry includes a descriptor tag, ICB tag, allocationdescriptor length, extension attribute, and allocation descriptor. “BP”in the drawing represents a bit position, and “RBP” represents arelative bit position.

The descriptor tag is a tag that shows the current piece of informationis a file entry. DVD-RAM includes a various types of tags such as a fileentry descriptor, a space bit map descriptor, or the like. Each fileentry includes a descriptor tag written as “261” showing that thecurrent piece of information is a file entry.

The ICB tag shows attribute information related to the current fileentry.

The extension attribute is information showing a higher-level attributethan the contents defined in the attribute information field in the fileentry.

The allocation descriptor field stores as many allocation descriptors asthe number of extents in the file. The allocation descriptor shows anLBN indicating a storage position of an extent in a file or a directory.FIG. 11B shows the data structure of the allocation descriptor. In thedrawing, the allocation descriptor includes data indicating an extentlength and includes an LBN indicating a storage position of an extent.Note that the upper two bits of the data indicating an extent lengthshows the storage status of the extent recording area, as shown in FIG.11C.

FIGS. 12A and 12B respectively show a detailed data structure of thefile identification descriptors for directory and file. These two typesof the file identification descriptors have the same format: eachdescriptor includes: management information, identification information,directory name length, an address showing the address, represented by anLBN, of the file entry of a directory or a file, information forextension, and directory name. With such an arrangement, an address of afile entry corresponding to a directory name or a file name isidentified.

(1-1-4) Minimum Size of AV Block

Here, the size of the AV block shown in the lower part of FIG. 4 isdescribed.

Each AV block except the last one in each zone is composed of 224 ECCblocks, where each ECC block has about 7 MB. To ensure the uninterruptedreproduction of AV data, the minimum size of AV block is determined inrelation with the buffer of the reproduction apparatus.

FIG. 13 shows a model of buffering of AV data into the track buffer, theAV data being read from the DVD-RAM disc by a reproduction apparatus.

In the upper part of FIG. 13, the AV data read from the DVD-RAM disc issubjected to the ECC process. The processed AV data is then temporarilystored in the track buffer (FIFO memory), and is sent to the decoder. Inthe drawing, “Vin” represents an input transfer rate (minimum value) ofthe track buffer (rate of data read from an optical disc), and “Vout”represents an output transfer rate (maximum value) of the track buffer,where Vr>Vo. In this model, Vin=8 Mbps and Vout=11 Mbps.

The lower part of FIG. 13 is a graph showing the change in the dataamount of the track buffer in this model. In the graph, the verticalaxis represents the data amount of the track buffer; the horizontal axisrepresents time.

The “T1” represents a time required for reading out the entire AV datarecorded in the pseudo consecutive record #j. In this period T1, thedata amount of the track buffer increases at the rate of (Vin−Vout).

The “T2” (also referred to as a jump period) represents the maximum timetaken by the optical pickup for jumping from the AV block #j to AV block#k (for example, it jumps from the innermost circuit to the outermostcircuit). The jump period includes the seek time of the optical pickupand the time required for the rotation of the optical disc to bestabilized. In this period T2, the data amount of the track bufferdecreases at the rate of Vout. This is the same in the period T4.

The size of the AV block is obtained as follows, where the size isrepresented as L bytes.

In the period T2, AV data is read from the track buffer. Only this isperformed. If the buffer capacity becomes 0 during this period, anunderflow occurs to the decoder. When this happens, the uninterruptedreproduction of the AV data cannot be ensured.

Here, to ensure the uninterrupted reproduction of the AV data (not togenerate the underflow), the following formula need be satisfied.

<Formula 1>

(storarge amount B)≧(read-out amount R)

The storarge amount B is the amount of data that has been accumulated inthe track buffer at the end of the period T1. The read-out amount R isthe total amount of data read during the period T2.

The storarge amount B is calculated using the following formula.$\begin{matrix}\begin{matrix}{\left( {{storage}\quad {amount}\quad B} \right) = \quad {\left( {{period}\quad {T1}} \right)*\left( {{Vin} - {Vout}} \right)}} \\{= \quad {\left( {{read}\quad {out}\quad {time}\quad {of}\quad {one}\quad {AV}\quad {block}} \right)*}} \\{\quad \left( {{Vin} - {Vout}} \right)} \\{= \quad {\left( {{AV}\quad {block}\quad {size}\quad {L/{Vin}}} \right)*}} \\{\quad \left( {{Vin} - {Vout}} \right)}\end{matrix} & \text{<Formula~~2>}\end{matrix}$

The read-out amount R is calculated using the following formula. It isconsidered that the maximum jump period Tj will be about 1.5 seconds inthe worst case. $\begin{matrix}\begin{matrix}{\left( {{Read}\text{-}{out}\quad {amount}\quad R} \right) = \quad {{T2}*{Vout}}} \\{= \quad {\left( {{maximum}\quad {jump}\quad {period}\quad {Tj}} \right)*{Vout}}} \\{= \quad {1.5\quad \sec*8\quad {Mbps}}} \\{= \quad {12\quad {megabits}}} \\{= \quad {1.5\quad {MB}}}\end{matrix} & \text{<Formula~~3>}\end{matrix}$

Replacing both sides of the Formula 1 respectively by Formula 2 andFormula 3 gives us the following formula.

<Formula 4>

(L/Vin)*(Vin−Vout)≧Tj*Vout

From the Formula 4, it is derived that the AV block size L shouldsatisfy the following formula. $\begin{matrix}\begin{matrix}{L \geqq \quad {{Tj}*{Vin}*{{Vout}/\left( {{Vin} - {Vout}} \right)}}} \\{\geqq \quad {1.5\quad \sec*11\quad {Mbps}*8\quad {{Mbps}/\left( {{11\quad {Mbps}} - {8\quad {Mbps}}} \right)}}} \\{\geqq \quad {44\quad {megabits}}} \\{\geqq \quad {5.5\quad {MB}}}\end{matrix} & \text{<Formula~~~5>}\end{matrix}$

From the above consideration, it is found that when AV data is recordedin a consecutive sectors of 5.5 MB in one AV block, uninterruptedreproduction is secured even if a jump occurs between AV blocks. Theminimum size of AV block to ensure uninterrupted reproduction is 5.5 MB.In the present embodiment, the AV block size is set to 7.2 MB. This isbecause a margin is included in the value, taking an occurrence of adisc error or the like into account. Also, the track buffer capacityshould have 1.5 MB at the minimum to prevent an occurrence of underflow.

(1-2-1) Entire System

FIG. 14 shows the construction of a system including the optical discrecording/reproduction apparatus of the present embodiment.

The system includes an optical disc recording/reproduction apparatus 10(also referred to as DVD recorder 10), a remote controller 6 used foroperating the DVD recorder 10, a DVD recorder display 12 connected tothe DVD recorder 10, and a receiver 9.

After the DVD-RAM disc is loaded, the DVD recorder 10 compresses thevideo/audio data which is included in the analog broadcasting waveswhich is received through the receiver 9, records the compressed data,with the AV block as the minimum unit, into the DVD-RAM disc, expandsthe compressed video/audio data, and outputs the expanded video/audiosignals onto a display 12.

(1-2-2) Hardware Structure of DVD Recorder 10

FIG. 15 is a block diagram showing the hardware structure of the DVDrecorder 10.

The DVD recorder 10 includes a control unit 1, an MPEG encoder 2, a discaccess unit 3, an MPEG decoder 4, a video signal processing unit 5, aremote controller 6, a bus 7, a remote controller signal receiving unit8, and a receiver 9.

The control unit 1 includes a CPU1 a, a processor bus 1 b, a businterface 1 c, and a main memory 1 d. The control unit 1 executes aprogram stored in the main memory 1 d to control the entire DVD recorder10 in terms of recording, reproducing, editing, etc. Especially, thecontrol unit 1 controls the DVD recorder in accordance with the filesystem when AV data is recorded in the DVD-RAM disc in the minimum unitsof AV blocks.

The MPEG encoder 2 compresses the video/audio data which is included inthe analog broadcasting waves received through the receiver 9 andgenerates an MPEG stream.

The disc access unit 3, having a track buffer 3 a, under the control ofthe control unit 1, records the MPEG stream received from the MPEGencoder 2 into the DVD-RAM disc via the track buffer 3 a, reads out theMPEG stream from the DVD-RAM disc, and outputs the read MPEG stream tothe MPEG decoder 4 via the track buffer 3 a.

The MPEG decoder 4 expands the compressed MPEG-stream which is read outby the disc access unit 3, and outputs the expanded video data and audiosignals.

The video signal processing unit 5 converts the video data output fromthe MPEG decoder 4 into video signals for the display 12.

The remote controller signal receiving unit 8 receives remote controllersignals from the remote controller 6 and informs the control unit 1 ofwhich operation the user has instructed.

The DVD recorder 10 is, as shown in FIG. 14, constructed based on thepremise that it is used as a replacement for a VTR used at home. Notlimited to the construction, when the DVD-RAM disc is to be used as arecording medium for computers, the following constructions arepossible. That is to say, the disc access unit 3 is connected, as aDVD-RAM drive apparatus, to a computer bus via an IF called SCSI or IDE.Also, the components other than the disc access unit 3 shown in FIG. 15are achieved or operated when the OS and the application program areexecuted on the computer hardware.

FIG. 16 is a block diagram showing the construction of the MPEG encoder2. As shown in the drawing, the MPEG encoder 2 includes a video encoder2 a, a video buffer 2 b for storing the output of the video encoder, anaudio encoder 2 c, an audio buffer 2 d for storing the output of theaudio encoder, a system encoder 2 e for multiplexing the encoded videodata and audio data respectively stored in the video buffer 2 b and theaudio-buffer 2 d, an STC (System Time Clock) unit 2 f for generatingsync clock signals for the encoder 2, and an encoder control unit 2 gfor controlling and managing these units.

The encoder control unit 2 g sends information such as the GOPinformation and the picture information to the control unit 1 shown inFIG. 15 every time a VOBU is generated in the encoding. Here, the GOPinformation includes the number of packs in the VOBU and the number ofpacks in the first I-picture in the VOBU. The packs mentioned here are,for example, video packs (V_PACK) and audio packs (A_PACK) shown in FIG.10, each having a fixed length of 2 KB. Accordingly, in the presentembodiment, the GOP information indicates the number of sectors assignedto the VOBU and the number of sectors assigned to first I-picture in theVOBU.

FIG. 17 is a block diagram showing the construction of the MPEG decoder4. As shown in the drawing, the MPEG decoder 4 includes a demultiplexor4 a for dividing MPEG streams into video streams and audio streams, avideo buffer 4 b for temporarily storing the divided video streams, avideo decoder 4 c for decoding the video streams stored in the videobuffer 4 b, an audio buffer 4 d for temporarily storing the dividedaudio streams, an audio decoder 4 e for decoding the audio streamsstored in the audio buffer 4 d, an STC (System Time Clock) unit 4 f forgenerating sync clock signals, an adder 4 g for adding offset values tothe sync clock signals, and selectors 4 h-4 j, for selecting either async clock signal or a sync clock signal added with an offset value andsupplying the selected signal to the demultiplexor 4 a, audio decoder 4e, and video decoder 4 c, respectively.

It should be noted here that the MPEG decoder 4 shown in the drawing maybe constructed the same as ordinary MPEG decoders in which the selectors4 h to 4 j and adder 4 g are not included.

(1-2-3) Function Block Diagram

FIG. 18 is a function block diagram showing the construction of the DVDrecorder 10 based on the functions of the components. Each functionshown in the figure is achieved after the CPU 1 a in the control unit 1executes the program in the main memory 1 d to control the hardwareshown in FIG. 14.

As shown in FIG. 18, the DVD recorder 10 is composed of a disc recordingunit 100, a disc reading unit 101, a file system unit 102, arecording/editing/reproducing control unit 105, a user IF unit 106, anAV data recording unit 110, an AV data editing unit 120, and an AV datareproducing unit 130.

The disc recording unit 100, on receiving a logical sector number andlogical data in units of sectors from the file system unit 102, recordsthe received logical data onto the disc in units of ECC blocks (eachblock composed of 16 sectors). If the logical data has less than 16sectors, the disc recording unit 100 reads the ECC block, executes theECC process, then writes the ECC block onto the disc.

The disc reading unit 101, on receiving a logical sector number and thenumber of sectors from the file system unit 102, reads data in units ofECC blocks, subjects the read data to the ECC process, the transfersonly necessary sector data to the file system unit. This is because byreading AV data in units of ECC blocks (each block composed of 16sectors), overhead is reduced. This is the same with the disc recordingunit 100.

The file system unit 102 includes an AV file system unit 103 for mainlywriting and editing AV files, and a common file system unit 104 forexecuting processes common to AV files and non-AV files. The file systemunit 102, on receiving commands from the AV data recording unit 110, AVdata editing unit 120, and AV data reproducing unit 130 in relation towriting or reading files, manages files on the optical disc in units ofsectors at the minimum.

Among various types of file management functions performed by the filesystem unit 102, (a) recording AV data, (b) deleting AV data, (c)recording non-AV data, and (d) deleting non-AV data are explained.

(a) Recording AV Data

On receiving a command to record AV data from the AV data recording unit110 or the like, the AV file system unit 103 updates the AV blockmanagement table by assigning an AV block written as “00” (unassigned)to the specified AV data. The AV file system unit 103 then records theAV data into the assigned AV block via the disc recording unit 100.After this, the AV file system unit 103 updates the AV block managementtable by writing the assigned AV block as “01” (for AV block), andupdates the space bit map by writing all the sectors included in theassigned AV block as “0” (assigned).

FIG. 19 shows the changes in the AV block management table and the spacebit map when AV data is recorded.

The left-hand side of the drawing shows change of the two-bit data inthe AV block management table showing the assignment status of the AVblock #n. The right-hand side of the drawing shows change of a part ofthe space bit map corresponding to the sectors included in the AV block#n. As shown in the drawing, when the status of the AV block #n in theAV block management table is changed from “00” (unassigned) to “01” (forAV data), the statuses of all the sectors included in the AV block #nare changed from “1” (unassigned) to “0” (assigned). With thisarrangement, each AV block does not include a mixture of AV data andnon-AV data, and a consecutive recording area is assigned to AV data asan AV block.

(b) Deleting AV Data

On receiving a command to delete AV data from the AV data editing unit120, the AV file system unit 103 updates the AV block management tableby writing an AV block recording the specified AV data as “00”(unassigned). The AV file system unit 103 then updates the space bit mapby writing all the sectors included in the current AV block as “1”(unassigned).

FIG. 20 shows the changes in the AV block management table and the spacebit map when AV data is deleted. As shown in the drawing, when thestatus of the AV block #n in the AV block management table is changedfrom “01” (for AV data) to “00” (unassigned), the statuses of all thesectors included in the AV block #n are changed from “0” (assigned) to“1” (unassigned).

(c) Recording Non-AV Data

On receiving a command to record non-AV data from therecording/editing/reproducing control unit 105, the common file systemunit 104 detects unassigned sectors which are written as “1”(unassigned) in the space bit map and are included in the AV blockswritten as “10” (for non-AV) in the AV block management table, andassigns the detected sectors to the specified non-AV data. The commonfile system unit 104 then records the non-AV data into the assignedsectors via the disc recording unit 100. After this, the common filesystem unit 104 updates the space bit map by writing the sectors havingrecorded the non-AV data as “0” (assigned). When not able to findunassigned sectors which are written as “1” (unassigned) in the spacebit map and are included in the AV blocks written as “10” (for non-AV)in the AV block management table, the common file system unit 104assigns sectors in an AV block written as “00” (unassigned) to thespecified non-AV data, updates the AV block management table by changingthe status of the AV block to “10” (for non-AV), and updates the spacebit map changing the statuses of the sectors to “0” (assigned).

(d) Deleting non-AV Data

On receiving a command to delete non-AV data from therecording/editing/reproducing control unit 105, the common file systemunit 104 updates the space bit map by changing the statuses of all thesectors recording the specified non-AV data to “1” (unassigned). When itis found from the AV block management table that one AV block isoccupied by the sectors with status “1” (unassigned) by the aboveprocess, the common file system unit 104 updates the AV block managementtable by changing the status of the AV block from “10” (for non-AV data)to “00” (unassigned).

The recording/editing/reproducing control unit 105 controls the entireDVD recorder 10. More specifically, the control unit 105 controlsdisplay of guidance which urges the user to operate, receivesinstructions from the user reacting to the guidance via the user IF unit106, and, in accordance with the user instructions, requests the AV datarecording unit 110, AV data editing unit 120, or AV data reproducingunit 130 to execute operations such as newly recording of AV data, andreproducing and editing of recorded AV data.

The user IF unit 106 receives instructions for operations from the uservia the remote controller 6, and informs the received user instructionsto the recording/editing/reproducing control unit 105.

The AV data recording unit 110, AV data editing unit 120, and AV datareproducing unit 130, on receiving a recording request from the controlunit 105, issue a command necessary for achieving respectively therecording, editing, and reproducing requests to the AV file system unit103.

(1-2-4) Commands Executed by File system Unit 102

Following are the commands supported by the file system unit 102.

The file system unit 102 receives various commands from the AV datarecording unit 110, AV data editing unit 120, AV data reproducingunit.130, and the recording/editing/reproducing control unit 105, andmanages the files in accordance with the received commands.

FIG. 21 shows a list of commands supported by the file system unit 102for the file management. The operations executed by the file system unit102 in response to the commands are described below.

CREATE: generate a new file on the disc, and return a fileidentification descriptor.

DELETE: delete a file from the disc. More specifically, the commandcancels the assignment of recording areas in units of AV blocks fordeleting an AV file, and cancels the assignment of recording areas inunits of sectors for deleting a non-AV file.

OPEN: obtain a file identification descriptor to access a file recordedon the disc.

CLOSE: close an opened file.

WRITE: record a file onto the disc. More specifically, the commandassigns recording areas in units of sectors for AV blocks for non-AVdata, and records data into the assigned sectors.

READ: read a file from the disc.

SEEK: move inside a data stream recorded on the disc.

RENAME: change a file name.

MKDIR: generate a new directory on the disc.

RMDIR: remove a directory from the disc.

STATEFS: inquire about the current state of the file system.

GET-ATTR: obtain an attribute of a file.

SET-ATTR: change an attribute of a currently opened file.

AV-WRITE: record an AV file onto the disc. More specifically, thecommand recording areas in units of AV blocks, and records data into theassigned AV blocks.

MERGE: merge two AV files on the disc into data in the memory.

SPLIT: split an AV file on the disc into two AV files.

SHORTEN: delete unnecessary part (an edge part) of an AV file on thedisc.

REPLACE: replace a part of an AV file with data in the memory.

SEARCH DISCON: detect whether a specified section includes adiscontinuous boundary (zone boundary), return “TRUE” if it includes thediscontinuous boundary; and return “FALSE” if it does not include thediscontinuous boundary.

It should be noted here that comands for recording AV data and non-AVdata are separately supported as the AV-WRITE command and the WRITEcommand.

The AV data recording unit 110, AV data editing unit 120, and AV datareproducing unit 130 achieves processes such as recording, editing, andreproducing by using combinations of the above commands.

(1-3) Recording/Deleting

Now, the operations of the DVD recorder 10 is described in detail. Theoperations are: (1-3-1) Manual Recording of AV Data, (1-3-2) ProgrammedRecording of AV Data, (1-3-3) Deleting of AV Data, (1-3-4) Recording ofNon-AV Data, and (1-3-5) Deleting of Non-AV Data.

(1-3-1) Manual Recording of AV Data

The manual recording is a recording immediately started when the userpresses the “Record” key on the remote controller without setting a timefor a programmed recording and sets two or three items on the screen.

For example, when the user presses the RECORD button on the remotecontroller 6 shown in FIG. 22, the display 12 displays a guidance image200 shown in FIG. 23 under the control of therecording/editing/reproducing control unit 105. When the user presses“1” and “Selection” keys on the remote controller while the guidanceimage 200 is displayed on the screen, a guidance image 201 for settingrecording conditions (in the present example, the “recording time” and“recording quality”) is displayed.

For setting the recording time, the user first moves the focus on thescreen onto either “no limit” or “specify” by operating the cursorbutton on the remote controller 6, then presses “Selection” button.Here, if the user selects “specify,” the screen changes to a guidanceimage for urging the user to input a time by operating the ten keybuttons. After the user specifies the time, the screen returns to theguidance image 201.

The “recording quality” as a recording condition relates to the bit rateand resolution of the MPEG data and has three types: “high,” “standard,”and “time-ensuring.” The bit rate and resolution for each quality typeis shown in FIG. 24.

Here, suppose the user selects “no limit” and “time-ensuring” quality onthe guidance image 201, and then presses the “Record” button on theguidance image 202, as a sample case of the manual recording. Thisseries of operations allows the manual recording to be started.

FIG. 25A is a flowchart showing the manual recording process.

The process starts as a notification that the user has pressed the“Record” button is sent to the recording/editing/reproducing controlunit 105 via the user IF unit 106. On receiving the notification, thecontrol unit 105 issues the CREATE command to the common file systemunit 104 (step 250). On receiving the command, the common file systemunit 104 returns the file identification descriptor when it is possibleto create a file. In this process, the file size is specified as themaximum size of the disc since “no limit” has been specified by the useras the recording time. Also, the recording/editing/reproducing controlunit 105 sends a file identifier and a parameter indicating the“time-ensuring” quality specified as the recording condition to the AVdata recording unit 110.

The AV data recording unit 110 instructs the MPEG encoder 2 to startencoding the video and audio data of a predetermined channel receivedthrough the receiver 9 and transferring the encoded MPEG data to thetrack buffer 3 a. While the above process is proceeding, the AV datarecording unit 110 issues the OPEN command to the AV file system unit103 (step 251) to allow the AV file system unit 103 to store the fileidentification descriptor given by the control unit 105 and informationon the file entry into a work memory (not illustrated) (the informationstored in the work memory is also referred to as “Fd” (File descriptor).

The AV data recording unit 110 issues the AV-WRITE command to the AVfile system unit 103 every time the track buffer 3 a stores apredetermined amount of MPEG data until it receives a stop command fromthe control unit 105 (steps 252 and 253). When receiving the stopcommand, the AV data recording unit 110 issues the AV-WRITE command(step 254), and issues the CLOSE command (step 255) to end the presentprocess. The AV-WRITE command is issued in step 254 to process theallocation descriptor of the last extent to be held in the Fd. The CLOSEcommand is issued in step 255 to write back the Fd in the work memoryonto the DVD-RAM disc as a file identification descriptor, a file entryor the like on the DVD-RAM disc.

Now, the data recording process executed by the AV-WRITE command isdescribed in detail.

FIG. 26 is a flowchart showing the process performed by the AV filesystem unit 103 having received the AV-WRITE command. Here, it ispresumed that the AV-WRITE command is issued to the AV file system unit103 together with three parameters specified. The three parametersrespectively indicate: the Fd having been opened by the OPEN command asdescribed above; the size of data to be recorded; and a buffer (in thisembodiment, the track buffer 3 a) storing the data. The Fd specified bythe parameter includes, as the file entry does, information of a storageposition of an extent and a length of the extent. The Fd is updatedevery time the AV-WRITE command is issued during the period between theopening and closing of the Fd. For the second or a subsequent issue ofthe AV-WRITE command, new data is additionally written, following thealready-recorded data.

As shown in FIG. 26, the AV file system unit 103 holds a counter forcounting for a size specified as a parameter. Until data of thespecified size is completely recorded (step 265:No), the AV file systemunit 103 assigns areas to the data, one sector by one sector, andrecords the data onto the disc. More specifically, when an opened filedoes not include already-recorded data (when the AV-WRITE command isissued once in a recording process); or when an opened file includesalready-recorded data (when the AV-WRITE command is issued twice in arecording process) and the data is recorded to the end of an AV block(step 266:No), the AV file system unit 103 detects an AV block withstatus “00” (unassigned) by referring to the AV block management table(step 267), changes the status to “01” (for AV data) (step 268), andchanges the statuses of all the sectors included in the AV block from“1” (unassigned) to “0” (assigned) (step 269).

When an opened file includes already-recorded data and the data is notrecorded to the end of an AV block (step 266: Yes), the AV file systemunit 103 proceeds to step 270.

The AV file system unit 103 fetches data having a size of one sectorfrom the track buffer 3 a, and records the fetched data to the firstsector of the newly assigned AV block or to a sector following adata-recorded sector on the DVD-RAM disc (step 270). The AV file systemunit 103 then updates the counter (step 271). The AV file system unit103 judges whether two sectors in which data was recorded most recentlyare consecutive sectors (step 272). The AV file system unit 103 judgesthat the two sectors are not consecutive when the two sectors are notphysically consecutive or when a zone boundary exists between thesectors. The presence of a zone boundary between the sectors is judgedby referring to the last-block-length table shown in FIG. 5. When it isjudged as negative in step 272, the AV file system unit 103 allows theallocation descriptor of Fd to hold, as one extent, the AV data recordedthe AV block immediately before the current AV block (step 273). When itis judged as positive in step 272, control returns to step 265.

When data of the specified size is completely recorded by repeating therecording of data into sectors (step 265: Yes), the AV file system unit103 allows Fd to hold the allocation descriptor of the last extentincluding the last-recorded sector (step 274) to end the “AV-WRITE”process.

As described above, on receiving the AV-WRITE command, the AV filesystem unit 103 assigns areas to the specified AV data in units of AVblocks which are each a consecutive area of about 7 MB. With thisarrangement, each extent, except the last extent, in each AV file inwhich AV data has been recorded has at least about 7 MB. This ensuresthe uninterrupted reproduction.

It is described for the sake of conveniences that data having a size ofone sector is recorded onto the DVD-RAM disc in step 270. However, inreality, data is recorded onto the DVD-RAM disc each time the trackbuffer stores data equivalent to one ECC block (16 sectors) in size.

(1-3-2) Programmed Recording of AV Data

The programmed recording is a recording process performed when the userpresses the “Record” key on the remote controller with a time forprogrammed recording set.

Here, it is presumed that the user selects “Specify” and “Time-Ensuring”on the guidance image 201, as a sample case of the programmed recording.This allows the programmed recording to be started.

FIG. 25B is a flowchart showing the programmed recording process.

The process starts as a notification that the user has pressed the“Record” button is sent to the recording/editing/reproducing controlunit 105 via the user IF unit 106. On receiving the notification, thecontrol unit 105 notifies the common file system unit 104 of thespecified time and issues the CREATE command to the same unit 104 (step256). On receiving the command, the common file system unit 104 returnsthe file identification descriptor when it is possible to create a file.In this process, the file size is specified to be the number of AVblocks corresponding to the specified time. Also, therecording/editing/reproducing control unit 105 judges whether areascorresponding to the specified time can be assigned based on whether afile identification descriptor has been sent (step 257).

Having judged that the areas cannot be assigned, the control unit 105ends the programmed recording process by performing the error process.

Having judged that the areas can be assigned, the control unit 105 sendsa file identifier. A specified time, and a parameter indicating the“time-ensuring” quality specified as the recording condition to the AVdata recording unit 110. On receiving these types of information, the AVdata recording unit 110 issues the OPEN command (step 259) when it isthe specified time to start recording (step 258). The subsequentprocesses of the AV data recording unit 110 are almost the same as thesteps 252-255 shown in FIG. 25A: issuing the OPEN command to the AV filesystem unit 103, repeating to issue the AV-WRITE command until it is theend time, and issuing the CLOSE command (steps 258-262).

As described above, the programmed recording starts after checkingwhether enough unassigned AV blocks for the specified time are availablefor the programmed recording.

Note that the order of the steps 256 and 257 may be reversed.

(1-3-3) Deleting of AV Data

Both AV files and non-AV files are deleted by the common file systemunit 104 when the DELETE command is issued: When receiving the DELETEcommand to delete a certain file, the common file system unit 104 judgeswhether the certain file is an AV file or a non-AV file by referring tothe extension of the file name and attribute information. The commonfile system unit 104 performs different processes on the AV blockmanagement table and the space bit map in accordance with the abovejudgement result.

FIG. 27 is a flowchart showing the process of deleting AV filesperformed by the common file system unit 104.

The common file system unit 104 judges whether an extent should bedeleted by referring to the file entry of the specified AV file (step240). Having judged as positive in this step, the common file systemunit 104 updates the AV block management table by changing the status ofthe AV block included in the extent from “01” (for AV data) to “00”(unassigned) (step 241), updates the space bit map by changing thestatuses of all the sectors included in the AV block from “0” (assigned)to “1” (unassigned) (step 242), and deletes the extent from file entry(step 243). When there is no extent to be deleted (step 240: No), thecommon file system unit 104 deletes the file identification descriptorand ends the AV file deletion process.

FIG. 28A shows deleted AV files. The upper part of the drawing showsthat AV files #1 and #2 are recorded in the AV blocks #10 to #14. The AVfile #1 is composed of two extents (AV files #1-1 and #1-2). The AV file#2 is composed of AV files #2-1 and #2-2. The lower part of FIG. 28Ashows that extents have been deleted from the AV file #1 of the AVblocks #11 and #14.

FIG. 28B shows the changes in the AV block management table and thespace bit map corresponding to the deletion shown in FIG. 28A. Theleft-hand side of FIG. 28B shows the state before deletion, and theright-hand side shows after deletion. In the AV block management table,statuses of the AV blocks #11 and #14 are changed from “01” (for AVdata) to “00” (unassigned) in accordance with the procedure shown inFIG. 27. In the space bit map, statuses of all the sectors included inthe AV blocks are changed from “0” (assigned) to “1” (unassigned). Itshould be noted here that the lower part of FIG. 28A is not intended toshow that the AV data included in the AV blocks #11 and #14 isphysically deleted. In reality, the AV data is dealt with as invaliddata by the AV file system unit 103.

(1-3-4) Recording of Non-AV Data

FIG. 29 is a flowchart showing the process of recording non-AV filesperformed by the common file system unit 104.

The common file system unit 104

On receiving the WRITE command from the recording/editing/reproducingcontrol unit 105, the common file system unit 104 judges whether thereis non-AV data to be recorded (step 261). Having judged as positive inthis step, the common file system unit 104 detects unassigned sectorswhich are written as “1” (unassigned) in the space bit map and areincluded in the AV blocks written as “10” (for non-AV) or “00”(unassigned) in the AV block management table (step 262). When thestatus of the AV block including the detected sectors is “00”(unassigned), the common file system unit 104 changes the status to “10”(for non-AV) (step 263), changes the statuses of the detected sectorsfrom “0” (assigned) to “1” (unassigned) (step 264), and records thenon-AV data into the detected sectors (step 265). The common file systemunit 104 then judges whether two sectors in which data was recorded mostrecently are consecutive (step 266). When it is judged as potive in step266, control returns to step 261; when it is judged as negative, thecommon file system unit 104 records into the file enty the allocationdescriptor of the extent including the sector immediately before thecurrent sector (step 268) to end the non-AV data recording process.

(1-3-5) Deleting of Non-AV Data

On receiving the DELETE command specifying a certain file from therecording/editing/reproducing control unit 105, and when the certainfile is non-AV file, the common file system unit 104 performs thedeletion process as follows.

FIG. 30 is a flowchart showing the process of deleting non-AV filesperformed by the common file system unit 104.

The common file system unit 104 judges whether an extent should bedeleted by referring to the file entry of the specified non-AV file(step 271). Having judged as positive in this step, the common filesystem unit 104 updates the space bit map by changing the statuses ofall the sectors included in the extent from “0” (assigned) to “1”(unassigned) (step 272).

The common file system unit 104 then judges whether the statuses of allthe sectors included in an AV block in the extent are “1” (unassigned)by referring to the AV block management table (step 273). When it isjudged so in the step, the common file system unit 104 updates the AVblock management table by changing the status of the AV block from “10”(for non-AV data) to “00” (unassigned) (step 274). The common filesystem unit 104 deletes the allocation descriptor of the extent from thefile entry (step 275), then returns to step 271. When it is judged thatthere is no extent to be deleted, the non-AV file deletion process ends.

FIG. 31A shows deleted non-AV files. The upper part of the drawing showsthat AV block #11 includes non-AV files #3 and #4. Each of the non-AVfiles #3 and #4 includes only one extent. The lower part of FIG. 31Ashows that the extent has been deleted from the non-AV file #3.

FIG. 31B shows the changes in the AV block management table and thespace bit map corresponding to the deletion shown in FIG. 31A. Theleft-hand side of FIG. 31B shows the state before deletion, and theright-hand side shows after deletion. In the AV block management table,the status of the AV block #11 remains to be “10” (for non-AV data) inaccordance with the procedure shown in FIG. 30 since file #4 remains inthe block. In the space bit map, statuses of all the sectors included inthe extent of AV block #11 are changed from “0” (assigned) to “1”(unassigned). It should be noted here that the lower part of FIG. 31A isnot intended to show that the non-AV data included in the file #3 isphysically deleted. In reality, the non-AV data is dealt with as invaliddata by the AV file system unit 103.

As apparent from the above description, the DVD-RAM of the presentembodiment includes the space bit map and the AV block management tableas a part of the file system management information. This constructionensures uninterrupted reproduction of AV data since consecutive areasare assigned in units of AV blocks.

In the DVD-RAM of the present embodiment, when an AV block is assignedto AV data, the statuses of all the sectors included in the AV block arechanged to “assigned” in the space bit map. With such a managementmethod, even if the DVD-RAM of the present invention is accessed by aconventional file system which supports only the space bit map, thefollowing problems are prevented: data is written into sectors includedin AV blocks for AV data, and consecutive sector areas assigned to AVdata are used and lost.

Concerning the sectors included in AV blocks assigned to non-AV data,only the statuses of the sectors in which data has actually beenrecorded are shown as “assigned” in the space bit map. That is to say,different from the case of the AV blocks assigned to AV data, thestatuses of the sectors in which data has not been recorded are notshown as “assigned” in the space bit map.

With the above construction, non-AV data can be recorded into an AVblock when there are unassigned areas in it even if the AV block hasalready been assigned to another kind of non-AV data. This enables theuse efficiency of the entire disc to be improved even if the discincludes both AV blocks for AV data and AV blocks for non-AV data.

In the above embodiment, the DVD recorder 10 is, as shown in FIG. 14,constructed based on the premise that it is used as a replacement for aVTR used at home. Not limited to the construction, when the DVD-RAM discis to be used as a recording medium for computers, the followingconstructions are possible. That is to say, the disc access unit 3 isconnected, as a DVD-RAM drive apparatus, to a computer bus via an IFcalled SCSI or IDE. Also, the components other than the disc access unit3 shown in FIG. 15 are achieved or operated when the OS and theapplication program are executed on the computer hardware. In this case,the disc recording unit 100, disc reading unit 101, and file system unit102 are mainly achieved as applications for enhancing the OS or thefunctions of the OS. Also, the other components other than these aremainly achieved as functions of the application programs. The variouscommands supported by the file system unit 102 are equivalent to servicecommands, such as a system call command, provided to the applications.

In the above embodiment, two bits are used to indicate the assignmentstatus of each piece of AV data in the AV block management table.However, the number of bits may be increased so that other kinds ofattribute information can be added.

FIG. 32 shows the second construction example of the AV block managementtable.

The AV block management table includes an arrangement of a plurality ofpieces of two-byte data which each shows the assignment information andattribute information. The upper four bits of each piece of two-bytedata are used for representing the assignment status of the AV blocks asdescribed in the present embodiment. The lower 12 bits represent thenumber of effective ECC blocks in the corresponding AV block. Forexample, the first AV block includes 224 (“E0” in hexadecimal notation)effective ECC blocks, and the sixth AV block includes 223 (“DF” inhexadecimal notation) effective ECC blocks.

As described above, in the AV block management table shown in FIG. 32,the number of effective ECC blocks for each AV block is recorded, thenumber of effective ECC blocks being the total number of ECC blocksincluded in each AV block from which the number of ECC blocks includingan address error is subtracted. If the file system unit 102 could notobtain the number of effective ECC blocks, the file system unit 102would be required to perform an address error process when recordingdata since it is impossible for the file system unit 102 to recognizethe amount of data that can be recorded into each AV block without theinformation. According to the AV block management table shown in thedrawing, the file system unit 102 is relieved from the complicatedaddress error process necessary when data is recorded.

Note that it is also possible to have another information whichindicates the ECC blocks or sectors in which address errors occur and toallow the AV file system to use the information.

It is also possible to reduce the amount of process performed by thefile system by using the most significant bit as a flag indicating“variable length” or “not-variable length” and by using the valueindicating the size of the AV block as an effective value only when theflag is on. This is possible when the probability of the occurrence ofaddress errors is very low and when almost all the AV blocks arerecognized as having a fixed length.

FIG. 33 shows the third construction example of the AV block managementtable.

The AV block management table includes an arrangement of a plurality ofpieces of four-bit data which each shows the assignment information andattribute information. The lower three bits of each piece of four-bitdata are used for representing the assignment status of the AV blocks asdescribed in the present embodiment. When the most significant bit is“1” (also referred to as a variable-length bit) the bit indicates thatthe current AV block has a variable length, when the bit is “0” the bitindicates a fixed length. Here, when an AV block has a fixed length, itindicates that the AV block includes 224 effective ECC blocks withoutaddress errors. Otherwise, the AV block has a variable length. An AVblocks has a variable length when the AV block includes an ECC blockhaving an address error or when the AV block is the last AV blockadjacent to a zone boundary.

The block length of a variable AV block is recorded in thevariable-length AV block table shown on the right-hand side of thedrawing. The table, replacing the last block-length table shown in FIG.5, includes, for each variable AV block, a block number and the numberof effective ECC blocks. As shown in the drawing, in the AV blockmanagement table, AV blocks with the variable-length bit are representedby boxes with slant lines. The number of effective ECC blocks for eachof these variable-length AV blocks is recorded in the variable-length AVblock table. With such an arrangement in which the variable-length AVblock table includes, for each variable AV block, a block number and thenumber of effective ECC blocks, it is possible for the file system torefer to the variable-length AV block table using the AV block numberwhen managing the AV blocks with variable-length flag in the AV blockmanagement table. Also, the third construction example, compared withthe second construction example, has a reduced size of the AV blockmanagement table.

When the physical size of each AV block is set as variable-length, it ispossible to perform the mapping of the sectors and the AV blocks withoutdifficulty by recording the sizes of all the AV blocks in thevariable-length AV block table. it is further possible to perform themapping of the sectors and the AV blocks without difficulty by recordingthe start sector number, track number, zone number in the AV blockmanagement table, instead of recording the physical sizes of AV blocksin the variable-length AV block table.

FIG. 34 shows the fourth construction example of the AV block managementtable.

The AV block management table includes an arrangement of a plurality ofpieces of two-byte data which each correspond to one AV block. Eachpiece of two-byte data indicates the number of files recorded in the AVblock, as well as the assignment status. The upper four bits are usedfor representing the assignment status of the AV blocks as described inthe present embodiment. The lower 12 bits indicate the number of files.Here, the number of files is 4095 at the maximum. Therefore, it ispossible to record 4095 files in one AV block.

Here, the lower 12 bits are referred to as a counter. Each countercorresponds to one AV block. It may happen that one file is divided andrecorded in a plurality of AV blocks when the file is AV file generallyhaving a large size or due to the area assignment even in case of anon-AV file generally having a small size. In this case, the counterregards a part of a file recorded in the AV file as one file. That is tosay, whether the AV file includes a whole file or a part of a file, eachcase is recognized as one file by the counter. Also, when a file isdivided and recorded in a plurality of extents in one AV block, the fileis regarded as one file.

The use of such a counter provides two merits to the management of theAV blocks. The first merit is that it becomes easier to judge whether torelease AV blocks for non-AV data. In the present embodiment, the filesystem unit 102 releases an AV block as unassigned when confirming byreferring to the space bit map that all the sectors included in the AVblock are unassigned. As understood from this, in the presentembodiment, to release an AV block, the space bit map is referred to.However, when the AV block management table includes counters as shownin FIG. 34, it is possible to release an AV block for non-AV data whenthe counter is “0.” This eliminates the necessity for referring to thespace bit map. It is needless to say that the space bit map should beupdated each time data is deleted from any sectors.

The second merit is that it becomes easier for a plurality of files tocoexist in one AV block for AV data. The term “coexist” indicates a casein which one AV file is divided into a plurality of AV files by editingnot that an AV file is added to an AV block in which another AV file hasalready been recorded. In this case, it is possible by using the counterto detect the presence of a plurality of AV files in an AV block and torelease an AV block when the counter is “0.”

In reality, it is enough to take into account a case where two filescoexist in one AV block. In this case, it is enough to set a flag,instead of a counter, indicating “coexist” of “not coexist.” In thiscase, the file system unit 102 may refer to the space bit map todetermine whether to release an AV block for non-AV data, as describedin the present embodiment, and may refer to the “coexistent” flag todetermine whether to release an AV block for AV data.

It is also possible for the fourth construction example to use thevariable-length bit described in the third construction example.Furthermore, it will also be possible for the AV block management tableto additionally include the size of AV block if the size of the data foreach AV block is increased to three bytes or more.

FIG. 35 shows the fifth construction example of the AV block managementtable.

In the present embodiment, the last AV block in each zone has a variablelength so as not a zone boundary is within one AV block. In the fifthconstruction example, each AV block has a fixed length of about 7 MB,and AV blocks are arranged from the start of the disc in order. In thiscase, like the AV blocks represented by slant lines in FIG. 35, some AVblocks may include a zone boundary. It is impossible to secure theuninterrupted reproduction for the AV blocks including a zone boundary.Therefore, it is required to manage the information indicating whethereach AV block includes a zone boundary. For this purpose, the fifthconstruction example allows the AV block management table to have a flagindicating whether each AV block includes a zone boundary.

The AV block management table shown in FIG. 35 includes an arrangementof a plurality of pieces of four-bit data which each correspond to oneAV block. The upper one bit indicates whether the corresponding AV blockincludes a zone boundary. The lower three bits indicate the assignmentstatus of the AV block. In this case, the file system unit 102 assignsthree consecutive AV blocks whose center AV block having a zone boundaryto one AV file, and does not assign one AV block having a zone boundaryto one AV file. With this arrangement, it is possible to ensure theuninterrupted reproduction even if an AV file is recorded into the AVblock having a zone boundary.

When it is presumed that only non-AV files can be recorded in the AVblocks including a zone boundary, the same number of AV blocks as thenumber of zone boundaries, that is 24 AV blocks should be prepared forthe non-AV files. The total capacity of the 24 AV blocks amounts to 164MB. That means, the capacity of the area in which AV files can berecorded reduces. As a result, it is desirable for the file system unit102 to manage the above-described three consecutive AV blocks togetherfor each zone boundary.

It is also possible for the AV block management table shown in FIG. 6 toinclude a discontinuous flag which indicates that the AV blocks beforeand after a zone boundary are not consecutive. With this arrangement, itwill be easier for the file system unit 102, when assigning twoconsecutive AV blocks, to judge whether the two consecutive AV blockshave a zone boundary in between since the unit 102 can obtain theinformation by referring to the AV block management table.

When a set of AV blocks for non-AV data is reserved in advance, with theset having a predetermined size, the mixed presence of the AV blocks forAV data and non-AV data is prevented. This makes it easier to assignconsecutive areas to AV data.

When a disc having been written by an AV file system is not compatiblewith discs having been written by another type of file system, and whenthe disc is accessed only by the AV file system, it is possible to writeas “assigned” the statuses of the sectors in which AV data has actuallybeen recorded, not the statuses of all the sectors included in AV blockswhose statuses are written as “for AV data.” This makes it easier tomanage the unassigned areas in the AV blocks.

In the present embodiment, the statuses of all the sectors included inan AV block for AV data are written as “assigned.” However, only thestatuses of the sectors in which AV data has actually been recorded maybe written as “assigned.” This makes it easier to manage the unassignedareas in the AV blocks though compatibility between discs having beenwritten by the AV file system and another type of file system issomewhat lost.

(2) Embodiment 2

Now, the optical disc and the optical disc recording/reproducingapparatus of Embodiment 2 are described.

(2-1) Optical Disc

Embodiment 2 differs from Embodiment 1 in that (1) pseudo consecutiverecords, instead of the AV blocks, are assigned to AV data to berecorded, and that (2) pseudo consecutive record assignment managementinformation is used instead of the AV block management table. Thedifferences (1) and (2) are described below in detail.

With regard to the above difference (1), in Embodiment 1, the entiredata recording area is almost fixedly divided into AV blocks each with afixed length in advance whether AV data has been recorded or not in thearea. In contrast, in Embodiment 2, AV blocks are not used. Instead,areas called pseudo consecutive records are dynamically assigned to AVdata, each pseudo consecutive record having a size greater than thefixed length described in Embodiment 1.

With regard to the above difference (2), in Embodiment 1, one AV blockmanagement table is used to manage the assignment states of all the AVblocks. In contrast, in Embodiment 2, the pseudo consecutive recordassignment management information for managing the pseudo consecutiverecord is recorded on the disc for each AV file.

Accordingly, FIGS. 1-3 and 8-12 used in Embodiment 1 also apply to theoptical disc of Embodiment 2. FIG. 4 can also be applied to Embodiment 2by deleting the AV blocks. Since in Embodiment 2, the othercharacteristics are the same as Embodiment 1: the partition region isdivided into a plurality of zone areas; and reading and writing of dataare performed in units of ECC blocks (each having 16 sectors). Also,although the AV management table shown in FIG. 6 is not used inEmbodiment 2, the sector management table (space bit map) is used aswell.

(2-1-1) Pseudo Consecutive Record

Each AV file in the present Embodiment is composed of one or more pseudoconsecutive records to ensure the uninterrupted reproduction. The“pseudo consecutive record” is defined as an area recording AV data orthe AV data recorded in the area, where the AV data may be whole orpartial, has a size greater than a size that ensures a consecutivereproduction, and the area is composed of consecutive sectors or ECCblocks. However, the skipping by the ECC block skip method is counted infor the consecutive sectors or ECC blocks.

According to the ECC block skip method, when a defective sector whichcauses an address error or the like is detected, the ECC block includingthe defective sector is skipped and data is written into the next ECCblock. This method is more suitable for the consecutive reproduction ofAV data than the linear replacement method in which when a similardefect sector is detected, data is written into a sector in areplacement area having been reserved in the same zone. This is becausea jump to the replacement area does not occur in case of the ECC blockskip method.

Each pseudo consecutive record includes ECC blocks the number of whichis represented by any integer. The start sector of each pseudoconsecutive record is the start sector of one of the ECC blocks. That isto say, each pseudo consecutive record is located within a single zone.The minimum size of the pseudo consecutive record is set to 224 ECCblocks (about 7 MB) to ensure the consecutive reproduction of AV data,as in the AV block in Embodiment 1.

The pseudo consecutive record assignment management information showingan assignment result of a pseudo consecutive record is generated andrecorded for each AV file. The pseudo consecutive record assignmentmanagement information may be recorded in the start of the correspondingAV file. However, in the present embodiment, the information is recordedas non-AV files respectively corresponding to the AV files. The pseudoconsecutive record assignment management information has a liststructure.

(2-1-2) Assignment of Pseudo Consecutive Records

Each piece of pseudo consecutive record assignment managementinformation (also referred to as management information) corresponds toan AV file and shows areas on the disc which are assigned as pseudoconsecutive records to the current AV file.

The optical disc recording apparatus assigns unassigned areas on theoptical disc as pseudo consecutive records to AV files prior torecording of the AV files.

FIG. 36A shows a specific example of the management information. FIG.36B shows a space bit map corresponding to the management informationshown in FIG. 36A.

In FIG. 36A, the management information is described as a tableincluding entries el and e2. Each entry includes, from left to right inthe drawing, a start sector number (LSN: Logical Sector Number), an endsector number, and an attribute. Attribute “0” indicates a pseudoconsecutive record; attribute “1” indicates an unassigned area. In thepresent example, the attribute is always “0.”

The area identified by the start and end sector numbers specified byeach entry indicates a series of sectors which has been assigned as awhole or a partial pseudo consecutive record.

Here, a relationship between the pseudo consecutive record and theextent which is managed in the file system is described. The pseudoconsecutive records and the extents correspond to each other in aone-to-one relation when the extent does not outstep a zone boundary; aplurality of pseudo consecutive records correspond to one extent whenthe extent outsteps a zone boundary. For example, when an extentoutsteps a zone boundary, two pseudo consecutive records are formedbefore and after the zone boundary, both corresponding to the extent.

(2-1-3) Pseudo Consecutive Record Assignment Management Information andSpace Bit Map

FIG. 36B shows a space bit map corresponding to the managementinformation shown in FIG. 36A. In the example shown in the drawing, bitscorresponding to sectors (sector numbers 6848-15983) of pseudoconsecutive area #1 are all “0” indicating “assigned.” It is desirablethat the management information and the space bit map are managedtogether so that they reflect each other, although they use differentunits to indicate the assignment states of the data area. The opticaldisc recording apparatus sets the bits in the space bit mapcorresponding to sectors assigned as pseudo consecutive areas to “0”indicating “assigned.”

(2-2) Recording/Reproducing Apparatus

Here, the optical disc recording/reproducing apparatus of Embodiment 2is explained.

(2-2-1) System and Hardware Structure

Embodiment 2 uses the same structures as Embodiment 1 in terms of thesystem structure shown in FIG. 14, the hardware structure of the DVDrecorder shown in FIG. 15, the structure of MPEG encoder 2 shown in FIG.16, and the structure of MPEG decoder 4 shown in FIG. 17.

Embodiment 2 differs from Embodiment 1 in that (1) pseudo consecutiverecords, instead of the AV blocks, are assigned to AV data to berecorded, and that (2) pseudo consecutive record assignment managementinformation is used instead of the AV block management table.Accordingly, a program different from the program is stored in the mainmemory 1 d shown in FIG. 15 for use in the present embodiment.

(2-2-2) Function Block Diagram

FIG. 37 is a function block diagram showing the construction of the DVDrecorder 10 of Embodiment 2 based on the functions of the components.Each function shown in the figure is achieved after the CPU 1 a in thecontrol unit 1 executes the program in the main memory 1 d to controlthe hardware shown in FIG. 14.

In FIG. 37, reference numerals similarly numbered as those in FIG. 18for Embodiment 1 designate like components, and a recounting of theirfunction will be omitted from the description of this embodiment.

Embodiment 2 differs from Embodiment 1 in that the file system unit 102,recording/editing/reproducing/control unit 105, and AV data recordingunit 110 shown in FIG. 18 are not used, but a file system unit 202,recording/editing/reproducing/control unit 205, and AV data recordingunit 210 are used instead.

The file system unit 202 differs from the counterpart in Embodiment 1 inthat it includes an AV file system unit 203 and a common file systemunit 204 instead of the AV file system unit 103 and a common file systemunit 104.

The AV file system unit 203 differs from the AV file system unit 103only in that it does not support the AV_WRITE command shown in FIG. 21.

The common file system unit 204 differs from the common file system unit104 only in that the WRITE command is used to write AV data as well asnon-AV data onto the disc. That is, the file system unit 202 does notdiscriminate between AV data and non-AV data, but deals with themequally. The AV data and non-AV data are treated differently by the AVdata recording unit 210, AV data editing unit 220, and AV datareproducing unit 230.

The AV data recording unit 210, AV data editing unit 220, and AV datareproducing unit 230, respectively on receiving a recording request, anediting request, and a reproducing request from therecording/editing/reproducing/control unit 205, issues necessarycommands to the AV file system unit 103.

The AV data recording unit 210, on receiving a recording request fromthe control unit 205, issues a command necessary for the requestedrecording to the AV file system unit 103, and also creates or updatesthe management information shown in FIG. 36A. More specifically, the AVdata recording unit 210, on receiving a recording request, searches forunassigned areas by referring to the space bit map and the managementinformation, assigns an area having a size greater than theearlier-mentioned fixed length of about 7 MB, and also creates a newpiece of management information shown in FIG. 36A. Here, when a pseudoconsecutive record has already been created, it is desirable that anarea following or as close as possible to the existent pseudoconsecutive record is assigned as a new pseudo consecutive record. TheAV data recording unit 210 then creates a new piece of managementinformation for the newly assigned area.

(2-3-1) Recording of AV Files

Recording of AV files in the DVD recorder 10 is described in detail.

FIG. 38 is a flowchart showing the recording process in the DVD recorderof the present embodiment.

When the user presses the RECORD button or when the “current time”reaches the start time of “programmed recording,” a notification ofrecording start is sent to the recording/editing/reproducing/controlunit 105 via the user IF unit 106.

On receiving the notification, the control unit 105 assigns an areahaving a size greater than the predetermined size (about 7 MB) as apseudo consecutive record (step 380). More specifically, the controlunit 105 refers to the space bit map and the management information todetect unassigned consecutive sector areas. The control unit 105 thenassigns the detected unassigned consecutive sector areas as a new pseudoconsecutive record. In doing so, when other AV data has already beenrecorded in the disc and when the AV data to be recorded continues fromthe existent AV data logically, the control unit 105 assigns aconsecutive recording area that continues from the already-assignedconsecutive recording area of the existent AV data, if it is possible.

The recording/editing/reproducing control unit 105 sends a fileidentifier and a parameter indicating the “time-ensuring” qualityspecified as the recording condition to the AV data recording unit 210.The AV data recording unit 210 instructs the MPEG encoder 2 to startencoding the video and audio data of a predetermined channel receivedthrough the receiver 9 and transferring the encoded MPEG data to thetrack buffer 3 a (step 381).

The recording/editing/reproducing control unit 105 issues the CREATEcommand specifying the newly assigned pseudo consecutive record to thecommon file system unit 204 (step 382). On receiving the command, thecommon file system unit 204 returns a new file identification descriptorwhen it is possible to create a file in the newly assigned pseudoconsecutive record.

After the above process, the AV data recording unit 210 issues the OPENcommand to the AV file system unit 203 (step 383) to allow the AV filesystem unit 203 to store the file identification descriptor given by thecontrol unit 105 and information on the file entry into a work memory(not illustrated) (the information stored in the work memory is alsoreferred to as “Fd” (File descriptor).

The AV data recording unit 210 issues the WRITE command to the AV filesystem unit 203 every time the track buffer 3 a stores a predeterminedamount of MPEG data (steps 385 and 386). The AV data recording unit 210continues to perform this process until it receives a stop instructionfrom the control unit 105 (step 384:Yes). Here, it is presumed that theWRITE command is issued to the system unit 203 together with threeparameters specified. The three parameters respectively indicate: the Fdhaving been opened by the OPEN command as described above; the size ofdata to be recorded; and a buffer (in this embodiment, the track buffer3 a) storing the data.

The Fd specified by the parameter includes, as the file entry does,information of a storage position of an extent and a length of theextent. The information represents the pseudo consecutive recordassigned in the step 380. The Fd is updated every time the WRITE commandis issued during the period between the opening and closing of the Fd.For the second or a subsequent issue of the WRITE command, new data isadditionally written, following the already-recorded data.

On receiving the stop instruction (step 384), the AV data recording unit210 issues the WRITE command (step 387). The AV data recording unit 210then issues the CLOSE command (step 388). The AV data recording unit 210further informs the AV file management information generating unit 112that a recording of an AV file (VOB) has ended (step 389). The AV datarecording unit 210 then refers to the Fd (extent) of the recorded AVdata to create or update the management information (step 390). That is,the AV data recording unit 210 creates a new piece of managementinformation when an AV file is recorded for the first time; the AV datarecording unit 210 updates the management information and the space bitmap when an AV file is additionally recorded. The created or updatedmanagement information is recorded into the disc as a non-AV file viathe common file system unit 204.

It should be noted here that the WRITE command is issued in step 387 torecord onto the disc the rest of the data in the track buffer. Also, theCLOSE command issued in step 255 is a command used to write back the Fdin the work memory onto the DVD-RAM disc as a file identificationdescriptor, a file entry or the like on the DVD-RAM disc.

As apparent from the above description, when recording AV data, the DVDrecorder of the present embodiment dynamically assigns areas as pseudoconsecutive records by referring to the space bit map and the managementinformation. As a result, compared with the DVD recorder of Embodiment1, the DVD recorder of the present embodiment can use the data area onthe optical disc more effectively since the data area does not includeAV blocks which are logically divided sections.

(3) Embodiment 3

Embodiment 3 differs from Embodiment 2 in that (1) the minimum size ofthe pseudo consecutive record can be dynamically changed, and (2) thepseudo consecutive record assignment management information is not used.The differences are described as follows.

With regard to the above difference (1), the DVD recorder 10 of thepresent embodiment determines the minimum size of the pseudo consecutiverecord in accordance with the bit rate of a video object to be encodedactually, while in Embodiment 2, the minimum size of the pseudoconsecutive record is set to a fixed length of about 7 MB to ensure theconsecutive reproduction of AV data.

With regard to the above difference (2), the DVD recorder 10 of thepresent embodiment does not use the management information. Instead, theDVD recorder 10 searches for unassigned areas by referring to the spacebit map to assign areas as pseudo consecutive records to AV data to berecorded.

(3-1) Minimum Size of Pseudo Consecutive Record

First, the reason for determining the minimum size of the pseudoconsecutive record as mentioned in the above difference (1) isexplained.

FIG. 39 shows a model of buffering of AV data into the track buffer, theAV data being read from the DVD-RAM disc by a reproduction apparatusreproducing a video object. This model is created based on minimumspecifications required for the reproduction apparatus. As far as thesespecifications are satisfied, the uninterrupted reproduction is ensured.

In the upper part of FIG. 39, the AV data read from the DVD-RAM disc issubjected to the ECC process. The processed AV data is then temporarilystored in the track buffer (FIFO memory), and is sent to the decoder. Inthe drawing, “TVr” represents an input transfer rate of the track buffer(rate of data read from an optical disc), and “Vo” represents an outputtransfer rate of the track buffer (decoder input rate), where Vr>Vo. Inthis model, Vr=11 Mbps.

The lower part of FIG. 39 is a graph showing the change in the dataamount of the track buffer in this model. In the graph, the verticalaxis represents the data amount of the track buffer; the horizontal axisrepresents time. The graph is based on the premise that a pseudoconsecutive record #j that has no defective sectors and a pseudoconsecutive record #k that has a defective sector are read in the order.

The “T1” represents a time taken for reading out the entire AV datarecorded in the pseudo consecutive record #j that has no defectivesectors. In this period T1, the data amount of the track bufferincreases at the rate of (Vr−Vo).

The “T2” (also referred to as a jump period) represents a time taken bythe optical pickup for jumping from the pseudo consecutive record #j to#k. The jump period includes the seek time of the optical pickup and thetime required for the rotation of the optical disc to be stabilized. Themaximum jump period is equal to the time taken for jumping from theinnermost circuit to the outermost circuit. In this model, it ispresumed that the maximum jump period is about 1500 mS. In this periodT2, the data amount of the track buffer decreases at the rate of Vo.

A period including three periods “T3” to “T5” represents a time takenfor reading out the entire AV data recorded in the pseudo consecutiverecord #k that has a defective sector.

Among these periods T3 to T5, the period T4 represents a time taken forskipping the current ECC block that has a defective sector and moving tothe next ECC block. The skipping to the next ECC block is performed wheneven one defective sector is found in the current ECC block (16sectors). That means, when a defective sector is found, the problem ofthe defective sector is solved by not using the whole ECC block (all 16sectors) including the defective sector, not by logically replacing thedefective sector by a replacement sector (replacement ECC block). Thismethod is called ECC block skip method which has been described earlier.The period T4 represents a disc rotation wait time, where the maximumdisc rotation wait time is equal to one complete rotation time of thedisc. In this model, it is presumed that the maximum disc rotation waittime is about 105 mS. In the periods T3 and T5, the data amount of thetrack buffer increases at the rate of (Vr−Vo). In the periods T4, thedata amount decreases at the rate of Vo.

The size of the pseudo consecutive record is represented as“N_ecc*16*8*2048,” where the “N_ecc” represents the total number of ECCblocks included in the pseudo consecutive record. The smallest value ofN_ecc, namely the minimum size of the pseudo consecutive record iscalculated through the following procedure.

In the period T2, AV data is read from the track buffer. Only this isperformed. If the buffer capacity becomes 0 during this period, anunderflow occurs to the decoder. When this happens, the uninterruptedreproduction of the AV data cannot be ensured. Here, to ensure theuninterrupted reproduction of the AV data (not to generate theunderflow), the following formula need be satisfied.

<Formula 6>

(storage amount B)≧(consumption amount R)

The storage amount B is the amount of data that has been accumulated inthe track buffer at the end of the period T1. The consumption amount Ris the total amount of data read during the period T2.

The storage amount B is calculated using the following formula.$\begin{matrix}\begin{matrix}{\left( {{storage}\quad {amount}\quad B} \right) = \quad {\left( {{period}\quad {T1}} \right)*\left( {{Vr} - {Vo}} \right)}} \\{= \quad \left( {{read}\quad {out}\quad {time}\quad {of}\quad {one}\quad {pseudo}} \right.} \\{\left. \quad {{consecutive}\quad {record}} \right)*\left( {{Vr} - {Vo}} \right)} \\{= \quad {\left( {L/{Vr}} \right)*\left( {{Vr} - {Vo}} \right)}} \\{= \quad {\left( {{N\_ ecc}*16*8*{2048/{Vr}}} \right)*}} \\{\quad \left( {{Vr} - {Vo}} \right)} \\{= \quad {\left( {{N\_ ecc}*16*8*2048} \right)*}} \\{\quad \left( {1 - {{Vo}/{Vr}}} \right)}\end{matrix} & \text{<Formula~~7>}\end{matrix}$

In this formula, “L” represents the size of the pseudo consecutiverecord.

The consumption amount R is calculated using the following formula.

<Formula 8>

(consumption amount R)=T2*Vo

Replacing both sides of the Formula 6 respectively by Formula 7 andFormula 8 gives us the following formula.

<Formula 9>

(N_ecc*16*8*2048)*(1−Vo/Vr)≧T2*Vo

From the Formula 9, it is derived that “N_ecc” representing the totalnumber of ECC blocks included in the pseudo consecutive record shouldsatisfy the following formula to ensure the uninterrupted reproductionof the AV data.

<Formula 10>

N_ecc≧Vo*Tj/((16*8*2048)*(1−Vo/Vr))

In this formula, “Tj” represents the jump period that has been describedearlier. The maximum jump period is about 1.5 seconds. “Vr” is a fixedvalue (In the reproduction apparatus model shown in the upper part ofFIG. 39, Vr=11 Mbps). Also, considering that the video object isrepresented by a variable bit rate, “Vo” is obtained from the followingFormula 11. That is, “Vo” is obtained from Formula 11 not as the maximumvalue of the physical transfer rate of the track buffer output, but as asubstantial decoder input rate for AV data represented by a variable bitrate. In Formula 11, concerning the pseudo consecutive record length,N_pack is the total number of packs included in the video object thatshould be recorded in N_ecc ECC blocks. $\begin{matrix}\begin{matrix}{{Vo} = \quad {\left( {{pseudo}\quad {consecutive}\quad {record}\quad {length}\quad ({bits})} \right)*}} \\{\quad \left( {{1/{reproduction}}\quad {time}\quad {of}\quad {pseudo}\quad {consecutive}} \right.} \\\left. \quad {{record}\quad \left( \sec \right)} \right) \\{= \quad {\left( {{N\_ pack}*2048*8} \right)*\left( {27{M/}} \right.}} \\\left. \quad \left( {{{SCR\_ first}{\_ next}} - {{SCR\_ first}{\_ current}}} \right) \right)\end{matrix} & \text{<Formula~~11>}\end{matrix}$

In the above formula, “SCR_first_current” is a time (in 1/(27 mega)seconds) at which the track buffer of the reproduction apparatus shouldoutput the first pack of the video object, and SCR_first_next is a time(in 1/(27 mega) seconds) at which the track buffer of the reproductionapparatus should output the first pack of the following video object.

As shown in the above Formulas 10 and 11, the minimum size of the pseudoconsecutive record can theoretically be calculated in accordance withthe bit rate of AV data.

Formula 10 cannot be applied to a case where any defective sectors existon the optical disc. Such a case is explained below in terms of thevalue of “N_ecc” required to ensure the uninterrupted reproduction, the“N_ecc” representing the number of ECC blocks in the pseudo consecutiverecord.

It is presumed here that the pseudo consecutive record includes ECCblocks with defective sectors the number of which is represented as“dN_ecc.” No Av data is recorded into the dN_ecc defective ECC blocksdue to the ECC block skipping which has been described earlier. The losstime Ts generated by skipping the dN_ecc defective ECC blocks isrepresented as “T4*dN ecc,” where “T4” represents the ECC block skiptime for the model shown in FIG. 39.

With the above description taken into account, to ensure theuninterrupted reproduction of the AV data even if defective sectors areincluded, the pseudo consecutive record need to include as many ECCblocks as represented by the following formula.

<Formula 12>

N_ecc≧dN_ecc+Vo*(Tj+Ts)/((16*8*2048)*(1−Vo/Vr))

As apparent from the above description, the size of the pseudoconsecutive record is calculated from Formula 10 when no defectivesector is included, and from Formula 12 when any defective sectors areincluded.

It should be noted here that when an AV data sequence is composed of aplurality of pseudo consecutive records, the first and last pseudoconsecutive records need not satisfy the Formula 10 or 12. This isbecause the last pseudo consecutive record has no subsequent AV data,and that the uninterrupted reproduction between the first and secondpseudo consecutive records is ensured by delaying the timing of thedecode start, namely by starting supplying data to the decoder after thetrack buffer stores a certain amount of data.

(3-2) Recording of AV files

Recording of AV files in the DVD recorder 10 is described in detail.

FIG. 40 is a flowchart showing the recording process in the DVD recorderof the present embodiment. The flowchart is the same as FIG. 38 exceptthat the step 380 is replaced with step 400 and the step 390 is deleted.

The flowchart of FIG. 40 is described concentrating on the differences.

When the user presses the RECORD button or when the “current time”reaches the start time of “programmed recording,” a notification ofrecording start is sent to the recording/editing/reproducing/controlunit 105 via the user IF unit 106.

On receiving the notification, the control unit 105 assigns an areahaving a size greater than the above-described minimum size as a pseudoconsecutive record (step 400). More specifically, the control unit 105calculates the actual bit rate of the video object using the Formulas 10and 11. However, here, a predetermined size satisfying the minimum sizemay be used instead for the sake of conveniences. The control unit 105refers to the space bit map and each allocation descriptor of the filemanagement area to detect unassigned areas on the optical disc, createsa free space list showing the detected areas, and assigns an area amongthe detected areas which is larger than the minimum size as a pseudoconsecutive record. In doing so, an area including a zone boundary istreated as two unassigned areas, before and after the zone boundary.

FIG. 41 shows a free space list. In the drawing, the “start sector”column shows the start sector numbers of the unassigned areas; the “endsector” column shows the end sector numbers of the unassigned areas; andthe “attribute” column shows whether the corresponding areas areassigned. The “Free” shown in the drawing indicates that thecorresponding area is not assigned.

Presuming the minimum size is determined to be about 7 MB (3500sectors), it is found that unassigned area c1 is smaller than thisvalue, and unassigned areas c2 and c3 are both greater than this value.In this case, the recording/editing/reproducing/control unit 105 assignsthe unassigned areas c2 and c3 as pseudo consecutive records.

The same steps as FIG. 38 follow the above step. It should be noted herethat when recording AV data, the AV data recording unit 210 uses theunassigned areas located on the innermost side first by referring to thefree space list, followed by the unassigned areas in order from theinnermost to the outermost areas of the optical disc. Also note that thefree space list is not recorded on the optical disc.

FIG. 42 is a flowchart detailing the procedure of assigning the pseudoconsecutive record performed in the step 400 of FIG. 40.

The control unit 105 refers to the space bit map and each allocationdescriptor of the file management area to detect unassigned areas on theoptical disc (step 421). In doing so, the control unit 105 may disregardareas that are so small to record AV data (e.g., several-hundredkilobytes in size).

The control unit 105 creates the free space list based on the detectedunassigned areas (step 422). In doing so, an area including a zoneboundary is treated as two unassigned areas, before and after the zoneboundary. It should be noted here that the control unit 105 judgeswhether an area includes a zone boundary by inquiring the AV file systemunit 103, that is, by issuing the SEARCH_DISCON command shown in FIG.21. The positions of zone boundaries on the optical disc are fixedly setin advance, and are stored and managed by the AV file system unit 103.

Furthermore, the control unit 105 determines the minimum size of thepseudo consecutive record using the Formulas 10 and 11 (step 423). Here,when defective sectors are found, the control unit 105 uses the Formulas12 and 11. To simplify this process, the control unit 105 may determinethe minimum size of the pseudo consecutive record using a bit rate of AVdata determined in advance in compliance with the picture quality (e.g.,a quality classified into “high, “standard,” and “and “time-ensuring”shown in FIG. 24), an expected rate of defective sectors, and a margin.

The recording/editing/reproducing/control unit 105 then assigns an areaamong the detected areas which is larger than the minimum size as apseudo consecutive record, and determines the recording order (step424). The order is determined to be, for example, from the innermostside to the outermost side of the disc so that the seek move is as smallas possible.

As described above, when recording AV data, the DVD recorder of thepresent embodiment dynamically assigns unassigned areas as pseudoconsecutive records by referring to the space bit map and eachallocation descriptor of the file management area. As a result,different from Embodiment 2, the DVD recorder of the present embodimentdynamically assigns pseudo consecutive records for recording AV data,without recording the pseudo consecutive record assignment managementinformation.

It should be noted here that in Embodiment 3, the free space list iscreated for each recording. However, the DVD recorder may create thefree space list when the optical disc is loaded into the optical discdrive, and may update the free space list each time the DVD recorderrecords AV data.

Also, the DVD recorder may create and record the free space list ontothe optical disc, refer to the recorded free space list before recordingAV data, and update the list after the recording of the AV data.

The present invention has been fully described by way of examples withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will be apparent to those skilled in the art.Therefore, unless such changes and modifications depart from the scopeof the present invention, they should be construed as being includedtherein.

What is claimed is:
 1. An optical disc recording apparatus for recordingvideo objects on an optical disc, wherein a recording area of theoptical disc is divided into a plurality of blocks, each of which iscomposed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidoptical disc recording apparatus comprising: a reading unit operable toread the sector information from the optical disc; a detecting unitoperable to detect a series of consecutive unassigned sectors on theoptical disc by referring to the read sector information, a total sizeof the series being no smaller than a predetermined size thatcorresponds to a data amount that ensures the reproduction apparatus foruninterrupted reproduction of the video object; and a recording unitoperable to divide and record a video object onto two or more series ofconsecutive unassigned sectors detected by the detecting unit, and thepredetermined size is the number of blocks which is represented as “N”in the following formula: N=Vo*Tj/((N_sec*8*S_size)*(1−Vo/Vr)), where“Tj” represents a maximum jump time of an optical pickup of areproduction apparatus, “Vr” represents an input transfer rate of atrack buffer of the reproduction apparatus, and “Vo” represents aneffective output transfer rate of the track buffer.
 2. The optical discrecording apparatus of claim 1 further comprising unit operable togenerate management information showing areas of the optical disc wherethe video object has been recorded by the recording unit.
 3. An opticaldisc recording method for recording video objects on an optical disc foruse with a reproduction apparatus, wherein a recording area of theoptical disc is divided into a plurality of blocks, each of which iscomposed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidoptical disc recording method comprising: a reading step for reading thesector information from the optical disc; a detecting step for detectinga series of consecutive unassigned sectors on the optical disc byreferring to the read sector information, a total size of the seriesbeing no smaller than a predetermined size that corresponds to a dataamount that ensures the reproduction apparatus for uninterruptedreproduction of the video object; and a recording step for dividing andrecording a video object onto two or more series of consecutiveunassigned sectors detected in the detecting step, and the predeterminedsize is the number of blocks which is represented as “N” in thefollowing formula: N=Vo*Tj/((N_sec*8*S_size)*(1−Vo/Vr)), where “Tj”represents a maximum jump time of an optical pickup of the reproductionapparatus, “Vr” represents an input transfer rate of a track buffer ofthe reproduction apparatus, and “Vo” represents an effective outputtransfer rate of the track buffer.
 4. The optical disc recording methodof claim 3 further comprising a step for generating managementinformation showing areas of the optical disc where the video object hasbeen recorded in the recording step.
 5. A computer-readable recordingmedium recording a program for recording video objects on an optical foruse with a reproduction apparatus, wherein a recording area of theoptical disc is divided into a plurality of blocks, each of which iscomposed of a set of N_sec consecutive sectors, each sector having asize of S_size bytes, the optical disc records sector informationshowing data assignment for each sector on the optical disc, saidprogram causing a computer to execute: a reading step for reading thesector information from the optical disc; a detecting step for detectinga series of consecutive unassigned sectors on the optical disc byreferring to the read sector information, a total size of the seriesbeing no smaller than a predetermined size that corresponds to a dataamount that ensures the reproduction apparatus for uninterruptedreproduction of the video object; and a recording step for dividing andrecording a video object onto two or more series of consecutiveunassigned sectors detected in the detecting step, and the predeterminedsize is the number of blocks which is represented as “N” in thefollowing formula: N=Vo*Tj/((N_sec*8*S_size))*(1−Vo/Vr)), where “Tj”represents a maximum jump time of an optical pickup of the reproductionapparatus, “Vr” represents an input transfer rate of a track buffer ofthe reproduction apparatus, and “Vo” represents an effective outputtransfer rate of the track buffer.
 6. The computer-readable recordingmedium of claim 5, wherein the program further causes the computer toexecute a step for generating management information showing areas ofthe optical disc where the video object has been recorded in therecording step.
 7. An optical disc recording apparatus in which anoptical disc is inserted, wherein a recording area of the optical discis divided into a plurality of blocks, each of which is composed of aset of N_sec consecutive sectors, each sector having a size of S_sizebytes, the optical disc records sector information showing dataassignment for each sector on the optical disc, said optical discrecording apparatus comprising: a reading unit operable to read thesector information from the optical disc; a detecting unit operable todetect a series of consecutive unassigned sectors on the optical disc byreferring to the read sector information, a total size of the seriesbeing no smaller than a predetermined size that corresponds to a dataamount that ensures the reproduction apparatus for uninterruptedreproduction of the video object; and a recording unit operable todivide and record a video object onto two or more series of consecutiveunassigned sectors detected by the detecting unit, and the predeterminedsize is the number of blocks which is represented as “N” in thefollowing formula: N=Vo*Tj/((N_sec*8*S_size)*(1−Vo/Vr)), where “Tj”represents a maximum jump time of an optical pickup of a reproductionapparatus, “Vr” represents an input transfer rate of a track buffer ofthe reproduction apparatus, and “Vo” represents an effective outputtransfer rate of the track buffer.
 8. The optical disc recordingapparatus of claim 7 further comprising unit operable to generatemanagement information showing areas of the optical disc where the videoobject has been recorded by the recording unit.